ÿ\VISTA\GVISTA.HLP
/* This is the VISTA help file.
/* USERS: Do NOT modify or delete this file.
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/* command in the Vista command file (VISTA.CMD).  The width of the
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?general

General     Information
-----------------------
VISTA  was  designed to
be  friendly  and comp-
lying, allowing  you to
concentrate   on    the
seismic  analysis prob-
lem at hand.  This is a
general introduction to
VISTA, for more inform-
ation,   consult   your
users manual.

VISTA   is   a  general
purpose  seismic  proc-
essing  program.    The
program   has  26  data
registers, each capable
of  containing numerous
traces.      Particular
traces   within  a reg-
ister  may be specified
using  "doublets" which
are defined as shown in
the following examples:
1) a[12-24]
 would specify the 12th
 to 24th traces of reg-
 ister "a".
2) a[12]
 would specify the 12th
 trace only of register
 "a".
3) a[-24]    
 would specify the  1st
 to 24th trace of  reg-
 ister "a".
4) a[] or a
 would  specify all  of
 register "a".

The   output  from  any
ŠVISTA  function  may be
directed  to  the input
register,  but the data
in  the input data will
be overwritten and lost
after  the command  has
executed.

Any  function  or input
prompt may be "escaped"
from with the ESC key.

VISTA  may  be operated
via  commands  or  with
the  menus provided  by
the function keys.
 F1 : Command MENU
 F2 : HELP information
 F3 : Register DATA
 F4 : Disk FILE's
If  characters  are  on
the  command line, they
take   precedence   and
menu    selection    is
ignored.     This    is
indicated  by a  change
in   the type  of arrow
on  the  menu.
The menu   may be  used
for selecting commands,
registers,  or   files,
provided    the   arrow
is  POINTING   at   the
item  being   selected.

Help  is  available for
your current command by
pressing F2.    Help on
Specific   topics    is
available   with    the
"HELP" command.

Á typicaì VISTÁ sessioî
mighô  involvå  readinç
seismiã  datá froí disë
(leô  uó  saù  iî  filå
DEMO)¬   plottinç  thió
datá iî á  window¬  anä
theî phaså  rotatinç by
ninetù    degreeó   and
replottinç  iî á seconä
verticaì window:

   read DEMO put a
   set window on       
Š   plot a v1
   filter a put b
   plot b v2
        
?absolute_value
ABS  Replace samples by
their absolute value

abs <a> put <b>

<a>  Input register
<b>  Output register

<b> = Abs(<a>)

Each   sample  of   the
output is the  absolute
value  of  the  corres-
ponding input sample.


?add
ADD   Add two registers

ADD  <a> with <b> put
     <c>

<a>  Input register 1
<b>  Input register 2
<c>  Output register

<c> = <a> + <b>

Each   sample   of  the
output  is  the sum  of
the       corresponding
samples   in  the   two
inputs <a> and <b>.

The input registers <a>
and <b> must  be of the
same length, or, if the
WINDOW  option   is  in
effect   the   windowed
lengths  must   be  the
same.     The    output
register    <c>    will
always  be of the  same
length  as   the  input
registers,    or    the
windowed inputs.

Two possibilities exist
regarding   number   of
traces in the inputs:
Š
<a>  and  <b>   may  be
multi-trace  registers,
in   which   case   the
number  of traces being
accessed   from    each
register  must  be  the
same.

e.g.  ADD  a[3-8]  with
      b[6-11] put c

<c> will contain traces
    1 - 6

        OR

one  of  the  registers
<a>  and  <b>   may  be
single  trace  (or  the
user may  request  only
one   trace   from    a
particular   register),
in   which   case   the
single  trace  operator
will  be treated  as  a
constant

e.g. ADD a[8] with b
     put c

<c>  will  contain   as
     many traces as
     register <b>, and
     the single trace
     a[8] will be added
     to  each   of  the
     traces in <b>


?agc
AGC  Apply  AGC Scaling

AGC <a> put <b>
    <length>

<a> Input register

<b> Output     register
    containing   scaled
    version of input

<length>  Length  (ms.)
          of AGC window

ŠExample:  AGC  <a>  put
          <b> <length>

Each   sample   of  the
output  is  simply  the
corresponding     input
sample  divided by  the
average   amplitude  of
all     the     samples
contained  in  a window
centred on that sample.
Scaling does  not start
until     the     first
non-zero   sample    is
encountered.   At   the
start  and  end  of the
trace,  the  first  and
last  half   window  of
data  is scaled by  the
value  computed for the
first and last window.


?amplitude_spectrum
AMPLITUDE-SPECTRUM

Compute       frequency
amplitudes

AMPL <a> put <b>

<a>  Input    register
     containing  time
     domain  traces

<b>  Output register-
     each  trace will
     contain frequency
     amplitudes

Example:   AMPL a put b

The  Fourier  transform
of   the    input    is
calculated.  The ampli-
tude  of  each  complex
Fourier          sample
(frequency   amplitude)
is  then calculated and
placed in  the  output.
Due  to  the nature  of
the   discrete  Fourier
transform,     it    is
suggested   that    the
input register  contain
Ša   minimum   of   1000
samples   to  ensure  a
reasonably   fine  fre-
quency  sampling  rate.
This can be done easily
by   creating  a   time
domain   register  with
1000 sample points (see
CREATE) and moving your
Input register into it.
(see MOVE)


?arc_tangent
ARC-TANGENT

Inverse  tangent  ratio
of two registers

ARC <a> and <b> put <c>

<a> Input    register
    containing values-
    The sine of some
    angles

<b> Second   input
    containing values-
    The cosine of some
    angles.

<c> Output register to
    contain arctan(a/b)
    - A set of angles.

This  function computes
the   arc  tangent   or
inverse  tangent  given
two   input   registers
which correspond to the
sine     and     cosine
respectively   of   the
final  desired   angle.
The signs  of the input
samples, both numerator
and   denominator   are
used  to determine  the
correct quadrant of the
final  computed  angle.
Note  that this command
can be  used  to create
the instantaneous phase
of a  trace  if  <a> is
the  90  degree   phase
rotated version of <b>.
Š

?autocorrelate
AUTO-CORRELATE

Compute an auto-
correlation function

AUTO <a> put <b>
     <length>

<a> Input register

<b> Output register
    containing auto-
    correlation

<length> length of
    autocorrelation in
    ms.

The   output   register
will contain the zeroth
and all  positive  lags
up  to <length> of  the
autocorrelation   func-
tion   of  each   input
trace


?change
CHANGE

Change register  header
information

CHANGE    <a>   <header
name>    <new  header
information>

<a> Name of register to
be changed

New information
(up to 19 characters)

<header name>
"NAME1"   First line of
register header  infor-
mation.
"NAME2"   Second   line
of    register   header
information.

<New header info> New
Šline of header infor-
ation.

Example: CHANGE a Name1
      LINE x 10ms shift

This command allows the
user   to   alter   the
header  information and
titles     which    are
associated   with  each
register.  The informa-
tion   is  changed   by
means    of    a   self
explanatory    question
and answer dialogue.


?clear
CLEAR

Zero samples in a
register

CLEAR <a>  <start time>
      <end time>

<a> Register to be
    cleared

<start time>
    Start  of window to
    be cleared

<end time>
    End of window to be
    cleared

Example: CLEAR b[13-24]
         0 1000

The   samples  of  each
trace  in   the   input
register  lying  within
the   specified  window
will be set to zero.

?constant
CONSTANT 

Applù  á constanô valuå
to a register.

CONÓ  <a¾  puô  <b¾    
     <value> <option>  
Š
<a> input register

<b> output register

<value¾  constanô valuå
         to be applied

<option> how to apply
         the constant:
         (A)DD
         (M)ULTIPLY
         (S)UBTRACT
         (D)IVIDE

Example:

   CONS a put b 1.5 s

Thå   constanô  1.µ  ió
subtracteä  froí   reg®
<a¾  anä  puô  iî  reg®
<b>.

Note: For this  command
you must type at  least
four characters.
    
?convolve
CONVOLVE

Convolve    two    time
series

CONV  <a> with <b>  put
      <c> <length>
      <start time>

<a>  First    input
     register

<b>  Second input
     register

<c>  Output   register
     containing
     convolution of <a>
     and <b>

<length> Length of
     output

<start time>
     start time of
     operator

Example: CONV  a with b
         put c 1000 -50

Š
The   operator  <b>  is
convolved    with   the
traces  in <a>, <b> may
be   a   single   trace
(operator)  or  may  be
multi-trace   in  which
case  it  must have  as
many  traces  as  there
are    in   <a>    (one
operator    for    each
trace).   The length of
the output will usually
be the same as that  of
the  input   <a>.   The
start  time  refers  to
the time to be assigned
to the first sample  of
the  operator.   For  a
causal operator (like a
spiking   decon  opera-
tor),  this start  time
will  normally be 0 ms.
For  a symmetric  (zero
phase)  operator,   the
start     time     will
normally     be     the
negative half length of
the operator.

Note: for this  command
you must type at  least
four characters.

?correlate
CORRELATE

Correlate   two    time
series

CORR  <a> with <b>
      put <c> <length>
      <start time>

Example:  CORR  a  with
  b[2] put c 2000  1000

See   CONVOLVE  for   a
description    of   the
parameters.   The  only                                                        .
difference    is   that
CORRELATE   does    not
time-reverse        the
operator.  Notice  that
the start  time defines
the beginning lag value
of   the   correlation.
This  should be set  to
Šone    half    of   the
correlation  length  if
you wish  the  0 lag to
be  in the centre.   By
setting <a> and  <b> to
the   same   trace,   a
two-sided         auto-
correlation   can    be
produced.         ( The
AUTOCORRELATE  produces
produces only  positive
lags.)


?cosine
COSINE

Compute  the cosine  of
register samples

COS  <a> put <b>

<a> Input register
    (degrees)

<b> Output register

The samples of register
<b>,  the  output,  are
simply  the  cosine  of
the       corresponding
samples   of   register
<a>, the  input,  which
are  assumed to  be  in
degrees( NOT radians).


?create
CREATE

Create a register

CREATE <a> 
       <sample rate>
       <start time>
       <end time>
       <domain>

<a> Register to be
    created

<sample rate>  Applies
    to time domain
    registers

Š<start time>
    Start time of
    register

<end time>
    End     time     of
    register

<domain> Time,
         amplitude,  or
         phase

Example: CREATE  b[1-6]
         4 0 1000 T

This command sets up  a
register     with     a
specified   number   of
traces   (6    in   the
example), a length (end
time minus start time),
sample   rate   and   a
domain     (time     or
frequency).   The  sam-
ples of each trace will
be zero.   This command
is normally followed by
the   MOVE    or   FILL
command.

?dbgraph
DBGRAPH

Graph an amplitude
spectrum in decibels.

DBGRAPH   <a>
 <low bound> <window>
 <freq1> <freq2>

<a> input register
 (must be amplitude
  spectrum)

<lo÷ bound¾  lower
bounä oæ ploô iî 
- dB.  The plot will
always start with 0
at the top and this
lower bound at the
bottom.

<window¾ Ploô window
if SET WINDOW ON has
been entered.          
Š
<freq1> First frequency
to graph.

<freq2> Last frequency
to graph.

Amplitude values are
grapheä    usinç    thå
following relationship:

               A
dB = 20 log    - 
           10  A
                max

where:

   A = amplitude
       at any frequency

   A   = max. amplitude
    max
   
?deconvolve
DECONVOLVE

Apply    zero    phase,
spiking  or  predictive
deconvolution.

DECON <a>   put   <b>
<type>
<analysis window start>
<analysis window end>
<length>
<pre-whitening> <lag>

<type>  "Z,  S  or  P".
Deconvolution   type  -
zero phase, spiking  or
predictive.

<analysis window start>
Window     used     for
autocorrelation

<analysis  window  end>
calculations  and hence
operator.    Default  =
entire trace.

<length>
Length     (ms.)     of
deconvolution  operator
Š
<pre-whitening>
Percentage    of   pre-
whitening   to    apply
before  decon.

<lag>
Prediction  lag.   This
parameter     is    not
required if options "S"
or "Z" are chosen.

Example:  DECON a put b
s 500 1500 60 6

An  operator  is   cal-
culated and  applied to
each trace of the input
register.  The operator
is  computed  from  the
auto-correlation of the
operator analysis win-
dow.       Note    that
the operator   is   not
saved in this  command.
If  the   operator   is
desired,    use     the
SHAPING-FILTER       or
WEINER command.


?delete
DELETE
Delete register
contents for re-use

DELETE  <a>
	or
DELETE  <a>  to  <d>

<a> Register to be
    deleted

<d> optional end 
  register for deleting
  a range of registers.

Example:  DEL a
	     or
	  DEL b to g

This command deletes  a
single  register  or  a 
range of registers.  To
delete   a   group   of 
registers,  the  entire
command must be entered
on  the  command   line
otherwise,  the  delete
command   defaults   to 
delete  only  a  single
register.
This command allows the
re-use  of a   register
which  contains   data.

?divide
ŠDIVIDE

Divide one register  by
another

DIV <a>  with  <b>  put
    <c>

<a> Input register -
    numerator

<b> Input register -
    denominator

<c> Output register

<c> = <a> / <b>

Each   sample  of   the
output  is  simply  the
quotient     of     the
corresponding   samples
in  the two inputs  <a>
and <b>.

The input registers <a>
and <b> must  be of the
same length, or, if the
WINDOW  option   is  in
effect   the   windowed
lengths  must   be  the
same.     The    output
register    <c>    will
always  be of the  same
length  as   the  input
registers,    or    the
windowed inputs.

Two possibilities exist
regarding   number   of
traces in the inputs:

<a>  and  <b>   may  be
multi-trace  registers,
in   which   case   the
number  of traces being
accessed   from    each
register  must  be  the
same

e.g.  DIV  a[3-8]  with
      b[6-11] put c

<c> will contain traces
    1-6
Š
     OR

one  of  the  registers
<a>   and  <b>  may  be
single  trace  (or  the
user  may request  only
one   trace    from   a
particular   register),
in   which   case   the
single  trace  operator
will  be  treated  as a
constant

e.g.   DIV a[8] with  b
       put c

<c>  will   contain  as
many traces as register

<b>,  and   the  single
trace   a[8]  will   be
divided by each  of the
traces in <b>


?dump_samples
DUMP

Dump  register  traces/
samples on the printer

Example:  DUMP <a>

<a> Register whose
    contents are to be
    dumped

All  information  about
the register, including
values,  is  dumped  to
the  printer.   If   no
printer  is   attached,
this command aborts and
control is  returned to
look   for   the   next
command.

?exponentiate

EXP

Exponentiate an input
register.              

ŠEXP <a> put <b>

<a> Input register

<b> Output register

Thå inpuô registeò will
bå   exponentiateä   tï
creatå    thå    outpuô
register.  That is:

    s = exp(s )
     o       i

where:

    s = output sample
     o
    s = input sample
     i
 exp = natural exponent

?exit_program
EXIT

Quit VISTA

EXIT

Example:  EXIT

Control is returned  to
MS-DOS.   All  contents
of  all registers  will
be lost.


?fill_register
FILL

Fill  a  register  with
specified values.

FILL <a>    <option>
     <Time> <Amplitude>
     <Time> <Amplitude>
     <Fill type> ....

<a>  Input  and  output
     register

<option>     "O"      -
Overwrite  -  only  the
specified  samples  are
changed.  Existing sam-
Šples are unaffected.

"Z"  - All samples  are
set to zero before FILL
starts

<Time>
Time  (ms.)  of  sample
value to be set

<Amplitude>   Value  of
sample.  Floating point
input  is   acceptable.
Pairs      of     time,
amplitude  will be read
until  a  time  outside
the    range   of   the
register (e.g.   -1) is
input.   Such an  entry
terminates    parameter
input for this command.

<Fill  type> "Z" -
Fill with zero  samples
between       specified
(time, amplitude)

"I"  -
Use   linear  interpol-
ation to create samples
between       specified
samples - straight line
at  start  and  end  of
trace.

"B"  -
Block    fill -     all
samples  from   present
one  (time,  amplitude)
to previous (closer  to
time  zero) one are set
to   the   same   value
(amplitude)

Example:  FILL a z  100
0.5  200  -0.25  z  300
0.125 z -99

This  command   can  be
used  to create data  -
or  to   change  single
samples   of   existing
data.     The    CREATE
command will usually be
used prior  to  FILL to
Šset  up  the   register
length,  sample   rate,
number of traces etc.
Several successive FILL
commands may be used on
the same register, thus
allowing  the  user  to
specify every sample of
a long register through
command  file  input  -
see    section 3     on
Macros.
NOTE:  that  the  <Fill
type> must be specified
after  the   first  two
pairs  of input  values
(time  and  amplitude).
Following the first two
pairs, the  <Fill type>
must be specified after
every  pair  of  (Time,
Amplitude)  unelss  the
times  are  within  one
sample  in  which  case
the input may simply be
a   list   of    (time,
amplitude)       pairs.

?filter
FILTER

Apply    a    band-pass
filter.

FILTER <a> put <b> <F1>
       <F2> <F3> <F4>

<a> Input register

<b> Output register
    which is filtered
    version of <a>

<F1> Low Truncation
     frequency (Hz)
Š
<F2> Low cut
     frequency (Hz)

<F3> High cut
     frequency (Hz)

<F4> High truncation
     frequency (Hz)

Example: FILTER a put b
         10 15 50 60

This  command takes the
Fourier   Transform  of
the  input data.  The 4
frequency    parameters
specify    an    Ormsby
filter which is applied
in the frequency domain
filtered by  an inverse
transform. The phase of
the data  is  unchanged
by  the  filter.    The
amplitude      spectrum
passed  between F2  and
F3.  Between F1 and F2,
and  between F3 and F4,
a   linear   slope   is
applied      to     the
amplitude spectrum.   A
Hanning    window    is
applied to  the  linear
slopes     to    reduce
"ringing".


?geophone_response
GEOPHONE-RESPONSE

Compute  a  theoretical
geophone response

GEOPH <a> <sample-rate>
       <length>
       <resonant-freq.>
       <damping-factor>

<a>
Output register (single
trace)  containing  the
computed    theoretical
geophone response.

<sample-rate>
Sample   rate  of   the
wavelet

<length>
ŠLength in  ms.   of the
wavelet (response).

<resonant-freq.>
Resonant  frequency  of
the geophone in Hz.

<damping factor>
A value to indicate the
damping  factor -   see
below.

This command calculates
the   geophone  impulse
response.  The resonant
frequency  is   usually
known  from  observer's
reports   or   manufac-
turer's specifications.

The  damping  factor is
not  usually   provided
and must be  calculated
using   the   following
information:

Name and Model of
Geophone
eg. Mark l-15A

Resonant Frequency
e.g. 10 Hz

Coil Resistance   Rc
e.g. 600 Ohms

Shunt resistance  Rs
e.g. 3600 Ohms

The two Resistances can
usually be  obtained by
calling   the  Geophone
manufacturer and asking
if   they   have    the
information  on record.
They  will require  the
crew, party number, and
shooting date.

Finally,   to  get  the
Damping we must look up
Šthe  geophone  manufac-
turer's   specification
sheets.   For each type
of phone,  they  give a
formula,   which  typi-
cally  looks  something
like this:

Open Circuit Damping

    Bo = 0.36


The total Damping is

    H = Bo + Bc

For the previous example
(Mark L-15A):

           1.68 Rc
H = 0.36 + -------
           Rc + Rs

         1.68 (600)
= 0.36 + ------------
         (600)+(3600)

= 0.36 + 0.24 = 0.60


Coil Current Damping

   Bc = 1.68 Rc

always turn out to be a
number in the Range
0.5 - 0.8.

?graphical_plot
GRAPH

Display  a  line  graph
with scale annotation.

GRAPH   <a>    <window>
<start time> <end time>

<a>   Register   to  be
      graphed.

<window>
      Plot  window,  if
      window has been 
Š      set on in SET.
      Choices are:
      h1,h2 (horiz.)
      v1,v2 (vert.)
      q1..q4 (quad)
      u1..u10 (user)

<start time>
      First time to
      graph
 
<end time>
      Last time to
      graph

Example:  GRAPH b(3)

The specified register,
or the  first  trace if
the register is  multi-
trace, is  displayed on
the  screen in the form
of a  line  graph  with
axes   and  appropriate
annotation   (Amplitude
vs. time) or (Amplitude
vs.   frequency).   The
<window>  parameter  is
optional  if  the  full
screen is being used  -
else  it  will  have  a
value as given above.
(See SET PLOT command).

The    two   parameters
<start  time>  and <end
time>   are   optional.
They may  be  specified
in   time   (ms.)    or
frequency         (Hz.)
depending  on the  type
of    register    being
plotted.


?help
HELP

Give help on specified
command.

HELP <command>

Example:  HELP <Decon>

ŠThis  command  provides
VISTA  help information
on the topic specified.


?hardcopy_plot
HARDCOPY

Dump the screen display
to the hardcopy  device
(printer).

     HARD

Example:  HARD

The    current   screen
display,   minus    the
border,  command   line
and menu annotation, is
dumped  to the hardcopy
device.    Appendix  II
describes GRAFPLUS, the
printing       software
package,  and  explains
how    to    set    the
parameters   for   true
scale hardcopy.


?info
INFO

Give information  about
a register

   INFO  <a>

<a> Register to display
    information about.

Example:  INFO a

Pertinent   information
about a  register (data
length,   sample   rate
etc.) is  displayed  in
the menu box at the top
left   corner   of  the
screen.


?instrument_response
INSTRUMENT-RESPONSE

ŠCompute      instrument
impulse response

INSTR <instrument
      filename> put <a>

This  command  reads  a
VISTA  instrument  res-
ponse  file   into  the
output register.

The    parameters   for
naming  the  instrument
response  file will  be
prompt   for   (if  the
filename     was    not
entered on the  command
line).

Parameters:
Instrument Type  (first
4 letters)

Low-cut frequency
(value 1-7)

High-cut frequency
(value 1-4)

Filter slopes
(value 1-2)

Notch filter in/out
(1/0)

disk drive contain-
ing file

The  information is not
computed, but read from
any  one  of  a  set of
disk  files  which  are
provided with the VISTA
distribution kit.

The  naming  convention
used  for  these  files
will   allow   you   to
quickly   select    the
desired     instrument,
filter   settings   and
slopes.

An  example  will  best
explain this convention
Š
File name: DFS4521O.SGY

The  first   4  letters
"DFS4"    specify   the
instrument type.

The  next   number  "5"
specifies the 5th.  low
cut  frequency from the
table    defining   the
filter   settings  etc.
available    for   each
instrument type.

The   next  number  "2"
specifies   the    2nd.
high cut frequency from
the table.

The  next  number   "1"
specifies    the   1st.
filter  slope from  the
table.

The   next  letter  "O"
specifies   that    the
notch  filter was  out.
The final suffix ".SGY"
is  mandatory  for  all
VISTA data files.

The  complete table  is                                                       .
given  below   for  all
currently     available
instruments

Inst. Response Table
--------------------

Instrument
  Type

DDS 888     1
DFS III     2
DFS IV      3
DFS V       4
MDS 10      5

Ins.  Low-Cut Filters
    1 2  3  4  5  6  7

1   0 6 12
2   0 8 12 18 27  -
3   0 8 12 18 27  -
Š4   0 3  5  8 12 18 27
5   0 9 12 15 18 24 30


Ins.  High-Cut Filters
      1   2   3   4

1     62 125
2     62 124   -   -
3     62 124   -   -
4     62 128 180  90
5    125


Ins.Filter Slopes Notch
       1   2      Freq.

1      24  78      60
2      18  36 -    60
3      18  36 -    60
4      not reqd.   60
5      18  36      60


Notes:

DDS  888
The filter  slopes  are
high cut.  The low  cut
slope is 18   dB/octave

A low cut of 12 Hz.  is
only  available  for  2
ms.  sample rate with a
high cut of 125  Hz and
a     slope    of    78
dB/octave.

DFS  III
The slopes are  for low
cut.    No   slope   is
required  if  an OUT (0
Hz.)  is used.  In this
case   the   slope   is
ignored.

DFS  IV
Same as for DFS III.

DFS V
The 180 Hz high  cut is
not available with  OUT
(0 Hz)  low  cut.   The
low  cut  slope  is  18
dB/octave.
Š
This   table   will  be
expanded  from time  to
time   as    instrument
information is received
and  incorporated  into
VISTA.


?inverse_fft
IFFT

Perform inverse Fourier
Transform

IFF <a> and <b> put <c>

<a>   Input    register
containing    amplitude
spectra

<b>     Second    input
containing        phase
spectra

<c>   Output   register
containing time series

This  command  combines
amplitude   and   phase
information  to produce
the  corresponding time
series.    Both   input
registers must have the
same number of  traces,
the  same  time  length
and sample  rate.   The
first  input   register
must be  defined  as an
amplitude spectrum type
and  the  second  input
registeò   musô  bå   á
phase spectrum.

?invert
INVERT

Invert reflectivity  to
acoustic  impedance  or
acoustic  impedance  to
reflectivity.

INV <a> put <b> <type>
<start value> <scale>  

Š<a> input register

<b> output register

<type> type of input:

  R = reflectivity
 (output will be 
  impedance)

  I = impedance
 (output will be
  reflectivity)

Noteº The next two
parameters are used
only if input is 
reflectivity.

<start value> initial
 impedance value for
 recursive calculation

<scale> The maximum 
 reflectivitù  valuå
 will be set to this
 value.                

 Thió commanä will
perforí recursive
inversioî oæ eitheò an
inpuô reflectivitù or
impedancå usinç the
followinç formulas:

          Z   - Z
           i+1   i
     R = ----------
      i   Z   + Z
           i+1   i

              1 + R
                   i
     Z   = Z  ------
      i+1   i 
              1 - R
                   i
where:

  Z = impedance
  R = reflectivity
  é ½ layeò subscript

?log
LOG                    
Š
Natural Logarithm

LOG <a> put <b>

<a> Input register

<b> Output register

Output register will be
thå  naturaì  logarithí
of the input register. 

?macro
MACRO

Execute  VISTA commands
from a disk file

   MACRO filename

Example:
MACRO  MIKE.MAC

To use this command,  a
disk   file   must   be
prepared    (using    a
standard PC-DOS editor)
containing valid  VISTA
commands   -   one  per
line.              When
executing   the   MACRO
command,   VISTA  reads
each  command  in  turn
from the specified disk
file,   displays   that
command  at the top  of
the screen in the usual
way and prompts for any
unspecified parameters.

VISTA continues to read
commands  until the end
of  file is reached, at
which    time    normal
operation is resumed.


?math_library
MATH

Compute    mathematical
functions (Exponential,
ŠLogarithm)

MATH  <a>  put <b>
    <function-name>

<a>  Input register

<b>  Output register

<function-name>
One of E = Exponential
or     N =      Natural
Logarithm

Example: Math a put b E

This  command  computes
the  desired   function
for each sample of  the
input  register.   Thus
if "E" is chosen,  each
output    sample     is
computed  as  Exp(input
sample).


?mean_scale
MEAN

Apply   mean  amplitude
scaling

MEAN   <a>    put   <b>
<scale>   <start  time>
<end time>

<a>  Input data

<b>  Output (scaled)
     data

<Scale>
Output   scale  factor.
(Average         output
amplitude   will   have
this value).  Default =
1.0

<Start   time>
Start   time  of   mean
scale window.
Default = Start time of
          register

<End time> End time
Šof mean  scale  window.
Default  =  End time of
            register

Example:  MEAN a put  b
          1.0 500 800

The    average   sample
value     within    the
specified   mean  scale
window  is   calculated
for  each trace of  the
register.   All samples
of  each trace are then
multiplied  by  (Output
scale    factor/average
sample value).

?mix
MIX

Perforí aî N-tracå
weighted mix.

MIX <a> put <b> <nmix>
<w1> <w2> . . . <wn>

<a> Input register

<b> Output register

<nmix> Number of traces
to use in mix.  Must be
an odd number between 3
and 11.

<w1> First weight

<w2> Second weight
 .
 .
<wn> Nth weight        

Thå MIØ command
performó á weighteä mix
oî aî inpuô seô of
seismiã traces®  The
samå numbeò oæ traces
wilì bå outpuô aó are
input¬ buô eacè output
tracå wilì bå the
weighteä suí oæ itself
anä (N-1©  neighbouring
traces¬ (N-1)/² oî each
side®  Foò enä trace    
Šmixing¬ traceó wilì be
duplicateä aó many
timeó aó necessarù from
thå firsô anä last
trace.  

Foò á ³ tracå mix¬  thå
formula would be:

 s  = w1 * s       +
  ok        i(k-1)

w2 * s  + w3 * s
      ik        i(k+1)

where:

   s = input trace
    i
   s = output trace
    o
   k = trace subscript

?move
MOVE

Move a  portion  of one
register to another

MOVE
<a>  put   <b>   <Start
time> <End time> <Start
time-destination>

<a> Input register

<b>  Output   register.
Unlike    most    VISTA
commands,  the   output
register  may   already
exist.   Thus  the user
can    partially    (or
completely!)  overwrite
existing data.

<Start time> See below

<End   time>   The  two
parameters,  start  and
end time  define a time
window  of  data to  be
moved  from  the  input
register.    The  times
refer  to   the   input
register.
Š
<Start
time-destination>
This parameter  defines
the time in  the output
register  at  which  to
place the MOVE data.

Examples:  (1)  MOVE  a
put b 0 1000 0

           (2)     MOVE
a(1-3)  put  b 400  600
400

           (3)     MOVE
a(1-3) put b(12-14) 400
600 400

This    command   moves
samples     from    one
register   to  another.
In example (1), all the
traces in register  "a"
are moved  to  register
"b" - we assume "a"  is
1000 ms. in length.

In example (2) 3 traces
of  "a"  are  moved  to
"b".   Also  note  that
only the  data lying in
the  window 400 to  600
ms. is moved.  Thus "b"
will have 3 traces each
200   ms.    long   and
labelled  as 400 to 600
ms. when plotted.

In   example  (3),   we
assume  that   register
"b" already exists  and
contains  at  least  14
traces and is more than
600 ms.  long.  In this
case   the   200    ms.
window  (from   400  to
600) of traces 1, 2 and
3 of "a" will overwrite
the   200  ms.   window
(from 400  to  600)  of
traces 12, 13 and 14 of
"b".

Common    sense   rules
Šapply with MOVE.   Thus
do not attempt to  move
data into  an  existing
register  which is  not
long  enough  or  which
does  not  have  enough
traces.

Scale    changes    are
almost certain to occur
with  MOVE,  especially
when   combining   data
from   two   or    more
registers (using two or
more   MOVE  commands).
The "PLOT SCALE FACTOR"
is  carried  with  each
register  and  in  most
cases    these    scale
factors are  different.
Thus  you are  strongly
advised to  apply  some
type      of      trace
equalisation     (MEAN)
following  a series  of
MOVE   commands   which
have  accessed  several
different registers.


?multiply
MULTIPLY

Multiply  one  register
by another

MUL <a> with <b> put
    <c>

<a>  Input register 1
<b>  Input register 2
<c>  Output register

   <c> = <a> x <b>

Each   sample  of   the
output  is  simply  the
product      of     the
corresponding   samples
in  the two inputs  <a>
and <b>.

The input registers <a>
and  <b> must be of the
same length, or, if the
ŠWINDOW   option  is  in
effect   the   windowed
lengths   must  be  the
same.     The    output
register    <c>    will
always be  of  the same
length   as  the  input
registers,    or    the
windowed inputs.

Two possibilities exist
regarding   number   of
traces in the inputs:

<a>  and   <b>  may  be
multi-trace  registers,
in   which   case   the
number  of traces being
accessed   from    each
register  must  be  the
same

e.g.  MUL  a[3-8]  with
      b[6-11] put c

      <c> will contain
      traces 1-6

     OR

one  of  the  registers
<a>   and  <b>  may  be
single  trace  (or  the
user  may request  only
one   trace    from   a
particular   register),
in   which   case   the
single  trace  operator
will  be  treated  as a
constant

e.g.   MUL a[8] with  b
       put c

<c>  will   contain  as
many traces as register
<b>,  and   the  single
trace   a[8]  will   be
multiplied  by  each of
the traces in <b>

?mute
MUTE Mute an arbitray
portion of an input
set of seismic traces

mute <a> put <b>
<taper length> <mode>
<trace1> <time1>
        .
        .
<traceN> <timeN>
<stop>

<a>  Input register

<b>  Output register

<taper length> Length
of linear taper to
apply between zeros
and live data
(default = 8 ms)

<mode> One of:
       (c)ommand
       (i)nteractive
Note:
 Interactive mode is
 not implemented at
 this time. The
 following parameters
 are needed with
 command mode:

<trace1> <time1>
  First trace/time
  pair.

<traceN> <timeN>
  Last trace/time
  pair.

<stop> Type a negative
 trace value to tell
 program that input has
 stopped.

The output  is  a muted
version  of the  input,
where   the   mute   is
defined  by  trace/time
pairs.  Mute times will
interpolated    between
those  given.   If  the
first  and last  traces
entered     do      not
correspond    to    the
actual  first  and last
traces,  the times will
Šbe  extrapolated.   The
area  above  the   mute
line will be zeroed.

Example:

mute a put b 8 c 1 300
 12 0 24 300 -1

In the above example, a
triangular   mute   has
been   applied   to  an
input  profile  with 24
traces.

?erase
ERASE

Erase the screen

ERASE

This    command    will
erase the  contents  of
the screen.

?noise
NOISE

Create  a  noisy   time
series

NOISE <a> <sample rate>
<length>      <mean>
<lambda>

<a>
Output         register
containing   a   single
noisy time series

<sample-rate>
Sample rate ms.

<length>
Length ms. of output

<mean>
Desired  mean value  of
all samples in the time
series

<lambda>
Parameter  for  Poisson
distribution.  Must  be
Šbetween 0 and 1.

This command computes a
set  of  noise  samples
using a  random  number
generator.  The samples
will  have   amplitudes
which   are  Bernoulli-
Gaussian   in   distri-
bution and have a  mean
value as  specified  by
the  user.  For a  pure
Gaussian  distribution,
set  lambda to  1,  and
for      a       sparse
distribution,       set
lambda  close  to zero.
(Note: A value of  zero
will result in all zero
samples).


?phase_spectrum
PHASE-SPECTRUM

Compute    phase    vs.
frequency

PHASE <a> put <b>
<zero reference>

<a> Input register

<b> Output register
    containing phase
    spectrum.

<zero reference>
    Time zero on the
    time series

Example:  PHASE a put b
          150

Like AMPL, this command
expects  an input  time
series and computes the
phase  angles  for each
frequency.  The  number
of          frequencies
calculated  is equal to
the power  of  2 higher
than the number of time
samples.     Thus   the
frequency     increment
Šbetween    samples   is
equal  to  the  Nyquist
frequency   divided  by
the number of frequency
samples.   As suggested
in  the  AMPL  command,
the user  may  wish  to
extend    the     input
register  to  a minimum
of   1000  samples   to
ensure   a   reasonably
fine          frequency
increment.   The  phase
angles   will   between
.S 0.5
    o          o
-180  and  +180   (i.e.
.S 1.0

wrapped phase).


?plot
PLOT

Display a  register  on
screen (Seismic plot)

PLOT    <a>    <window>
<Start time> <End time>

<a> Register   to  be
    plotted

<window> specifies plot
window if window has
been set on in SET.

<start   time>    Start
plotting at this time
(msec)

<End time> End plotting
at this time (msec)

Example:  PLOT a v2
  500 700
 
The mode of  display is
determined    by    the
various      parameters
PLOT-MODE,  TIME-SCALE,
TRACE-SCALE,   POLARITY
etc.,    which     have
default    values    on
starting   VISTA,   and
which can be changed at
Šany time using  command
SET.


?read_file
READ-FILE

Read a  SEGY  disk file
into a register

 READ
<filename> put <a>

<filename>
Filename    of    data.
Example     DEMO     or
DEMO.SGY   The   suffix
".SGY"  is  assumed  if
omitted.

<a>  Register  in which
     to put the file

Example:  READ DEMO put
          a

When      VISTA      is
activated, the  default
directory  is the VISTA
directory.    Thus  all
data  files  should  be
placed  there prior  to
running  VISTA.   It is
possible   to    access
floppy  diskette  files
directly by  specifying
a   filename   such  as
"A:DEMO.SGY" .      The
file must  contain data
in standard SEGY format
as detailed in Appendix
III.   If the data  has
been created by program
SEGYFILE  on a VAX  and
transferred  to  the PC
using  KERMIT, it  will
be   in   the   correct
format.     Again   see
Appendix     III    for
complete details.

Note that  the  maximum
size  of disk file is 8
Mb.   -  or   2,000,000
floating  point samples
Š(4 bytes per sample).


?resample
RESAMPLE

Resample a register

RES <a>  put  <b>  <new
sample rate>

<a> Input register

<b>   Output   register
with new sample rate

<New sample rate>
Desired output sample
rate

Example: RES a put b 2

This  command  uses the
Fourier   Transform  to
resample  the  contents
of  the input register.
The  resampling  may be
finer    (more   output
samples than  input) or
coarser.   Only  ratios
of 1, 2, 4, or 8 may be
used.  Thus  resampling
from 2 ms.   to  16 ms.
(ratio of 8) or from 32
ms. to 4 ms.  (Ratio of
8)  is ok but 1 ms.  to
32 ms. is not.

Note   that    if   the
sampling  is   coarser,
(fewer output samples -
higher   sample   rate)
those frequencies which
exceed the new (output)
anti-aliasing frequency
will  be  filtered  out
(i.e. set to zero).


?rms
RMS  Apply RMS scaling

RMS
<a>  put   <b>  <scale>
<start time> <end time>
Š
<a> Input register

<b>   Output   register
(Rms  sealed version of
<a>)

<scale> Scale factor
Default = 1.0

<start time>
Start time of Rms scale
window   Default =
Start time of register

<end time> End time of
Rms scale window
Default = End time of
register

Example:  RMS  a  put b
1.0 500 800

This     command     is
identical  to  MEAN  as
far as parameters  etc.
The  type   of  scaling
employed  uses the Root
Mean  Square  amplitude
as   opposed   to   the
average  amplitude   in
MEAN.    That  is,  all 
samples of  each  trace 
are    multiplied    by
( scale factor  /  root 
mean square amplitude )
where the  " root  mean
square  amplitude "  is 
the square  root of the 
average  of  the  input
squared  amplitudes.


?rotate_phase
ROTATE

Apply         specified
constant          phase
rotation.

ROTATE   <a>   put  <b>
<angle>

<a> Input register

Š<b>   Output   register
consisting    of    <a>
rotated by the  desired
amount.

<angle>       Specified
rotation    angle    in
degrees.

Example:  ROT a put b
          90

The    data    in   the
specified         input
register  are   Fourier
transformed          to
(amplitude,  phase) vs.
frequency.          The
specified      rotation
angle   (constant)   is
added to the calculated
phase  angle  at   each
frequency.  The inverse
transform  to  time  is
then  computed  and the
result  placed  in  the
output register.


?save_register
SAVE-REGISTER

Write the contents of a
register to a permanent
disk file.

SAVE  <a>  put
      <filename>

<a>   Register   to  be
saved to disk

<filename>    Name   of
saved disk  file.   The
full   name   will   be
filename.SGY,  but .SGY
may be omitted.

Example:  SAVE  a[1-12]
          put TEST1.SGY

Like   READ,  this
command   uses   MS-DOS
filenames.   The   same
comments apply here  as
Šmade   in    the   READ
description.


?set-up_plot
SET-UP

Set  various   plotting
parameters

SET <option> <value>

 <option>  WINDOW
           DIRECTION
           FILL
           POLARITY
           AMPLITUDE
           EXCURSION
           CLIP-FACTOR
           TRACE-SCALE
           TIME-SCALE
           OVERTIME
           OVERTRACE
           SHOW

<value>      -
Dependent  on <option>.
See table below.

Examples:  SET  PLOT H
           SET  TIME 7.5
           SET  EX 1.5
           SET  TR 12

This  command sets  the
plot  scales  etc.  for
VISTA.    On  entry  to
VISTA,   defaults   are
established which  will
automatically     scale
plots   to   fill   the
screen   (or   window).
Once "SET",  parameters
stay set until changed.
The  automatic  default
can  be  re-established
by  specifying a  value
of 0 e.g.  "SET TIME O"
or "SET TR O".



Option                 
------

ŠWINDOW

ON Windows set on.
   Choices in plot
   or graph are:

f = full screen
h1,h2 = horizontal
v1,v2 = vertical
q1..q4 = quad
u1..u10 = user defined

OFF Windows turned off.
    Only full screen is
    available.

DIRECTION
L
Left to right plotting
R
Right to left plotting
eg.  set dir l

FILL
ON
Traces will be filled.
OFF
Trace filling is
suppressed.
eg.  set fill off

POLARITY
N  Normal-
   peaks show positive
   samples
R  Reverse
eg.  set pol r

AMPLITUDE
a
An amplititude of size
"a"  will  be  plotted
with a trace excrusion
equal to  the  current
value   of   EXCURSION
("e")  A  value  of  0
implies      automatic
scaling.
eg.  set amp 10000

EXCURSION
e
The  number  of  trace
positions   used    to
represent an amplitude
Šequal  to the  current
value   of   AMPLITUDE
("a").
eg.  set ex 2.5

CLIP
c
A     trace     sample
exceeding  "c"  traces
excursion    will   be
clipped.
eg.  set cl 2.0

TRACE-SCALE
n
Number  of traces  per
inch.  A  value  of  0
implies      automatic
scaling.
eg.  set tr 12

TIME-SCALE
t
Number of  inches  per
second.   A value of 0
implies      automatic
scaling.
eg.  set ti 7.5

OVERTIME
Time overlap is set.
Must be between 0% and
100 %. (Default = 0%)

OVERTRACE
Trace overlap is set.
Must be between 0% and
100 % (Default = 0%)

SHOW
Display   the  current
values   of   all  the
"SET" parameters.
eg.  set show


?shaping_filter
SHAPING-FILTER


Compute     a    Wiener
Shaping Filter

SHAP  <a> with <b>  put
<c>     <Filter-length>
Š<Lag> <Prewhitening>

<a> Input register

<b> Second input
register=Desired output

<c> Output  register  =
Filter    which    when
convolved with <a> will
shape <a> to look  like
desired output <b>.

<Filter-len> Length ms.
of computed filter.

<Lag>  Lag ms.  to  use
when  computing   cross
correlation  of   input
with desired output.

<Prewh.> Percentage  of
pre-whitening   to   be
used      on      input
auto-correlation  prior
to   computing   Wiener
filter.

Example: SHAP a with  b
put f 50 0 .1

This command computes a
filter ( or filters  if
the    input    is    a
multi-trace   register)
which  presumably  will
be  convolved some time
later  with  the  input
traces. The filters are
designed such that they
will shape the input to
the  desired  output in
the least squared error
sense.

Both  input   registers
must  be  time  series,
and   have   the   same
number  of traces,  the
same  length,  and  the
same sample rate.   The
filter  length  must be
less   than  the  input
length.

Š
?sine
SINE

Compute  the   sine  of
register samples

   SIN <a> put <b>

<a> Input register
    (in degrees)

<b> Output register
    (sin of <a>)

The samples of register
<b>,  the  output,  are
simply the sine  of the
corresponding   samples
of  register  <a>,  the
input,    which     are
assumed   to    be   in
degrees( NOT radians).


?square_root
SQUARE-ROOT

Compute the square root
of register samples

  SQU <a> put <b>

The samples of register
<b>,  the  output,  are
simply the square  root
of  the   corresponding
samples   of   register
<a>, the input.

?stack
STACK

Stack traces in an 
input register.

STACK <a> put <b> <N>

<a> Input register

<b> Output register

<N> Number of traces to
    stack per output
    trace.
Š
Thió  commanä  performó
aî   N-tracå   verticaì
stacë   oî  thå   inpuô
traces®   Thå numbeò oæ
output traces will be:

                NTRI
NTRO = ceiling  ----
                 N
where:
     
   NTRO = number of
      output traces

   NTRI = number of
      input traces

     N = Number to
         stack

ceiling = Next 
   highest integer

e.g.:

 If  NTRI = 24

 Then, for             

   N = 24, NTRO = 1

   N = 6 , NTRO = 4

   N = 5 , NTRO = 5
    stacked 5,5,5,5,4

Note: For this  command
you must type at  least
four characters.

?static_shift
STATIC-SHIFT

Apply a time shift

STATIC   <a>  put   <b>
         <time shift>

Example: STATIC a put b
         -10

The data  in  the input
register  will be  time
shifted     by      the
specified  amount.    A
negative  value implies
movement     of    data
towards   time    zero.
ŠZero  samples   replace
lost data.

Note: For this  command
you must type at  least
four characters.

?subtract
SUBTRACT

Subtract  one  register
from another

SUB <a>  with  <b>  put
<c>

<a>  Input register 1
<b>  Input register 2
<c>  Output register

<c> = <a> - <b>


Each   sample   of  the
output  is  simply  the
difference    of    the
corresponding   samples
in the two  inputs  <a>
and <b>.

The input registers <a>
and <b> must  be of the
same length, or, if the
WINDOW  option   is  in
effect   the   windowed
lengths  must   be  the
same.     The    output
register    <c>    will
always  be of the  same
length  as   the  input
registers,    or    the
windowed inputs.

Two possibilities exist
regarding   number   of
traces in the inputs:

<a>  and  <b>  may   be
multi-trace  registers,
in   which   case   the
number of  traces being
accessed    from   each
register  must  be  the
same

e.g.   SUB a[3-8]  with
       b[6-11] put  c

Š      <c>  will contain
       traces 1-6

     OR

one  of  the  registers
<a>   and  <b>  may  be
single  trace  (or  the
user  may request  only
one   trace    from   a
particular   register),
in   which   case   the
single  trace  operator
will  be  treated  as a
constant

e.g.  SUB  a[8]  with b
put c

<c>  will  contain   as
many traces as register
<b>,  and the traces in
<b> will be  subtracted
from  the single  trace
a[8].


?vibroseis_sweep
VIBROSEIS-SWEEP

Create   a    Vibroseis
sweep   -   linear   or
non-linear

VIBR  <a> <sample rate>
<length>         <start
freq.>   <end    freq.>
<power>

<a>   Output   register
(single    trace)    to
contain   the  computed
vibroseis sweep.

<sample  rate>
Sample  rate of  output
sweep.

<length>
Length     (ms.)     of
generated sweep.

<start  freq.>
Start frequency (Hz.)

Š<end    freq.>
End frequency (Hz.)

<power>
Exponent (n) to use for
non-linear   case  (see
expression  below)
This   equates   to   a
3dB/octave  x n ramp on
the  amplitude spectrum
of the sweep

Example: VIBR a 4 8000
         20 80 0

This  command  computes
linear   or  non-linear
sweeps   following  the
paper  by  Landrum  and
Norris         (Western
Geophysical).       The
instantaneous frequency
is defined by:

.S 0.5
        n+1       1/n+1
F (t)=[F   +t/t A]
 i      s      L

.S 1.0

.S 0.5
           n+1   n+1
Where A = F   - F
           e     s

.S 1.0

The instantaneous phase
is      derived      by
integrating  the  above
expression          and
multiplying by 2 .  The
sweep  is  then  simply
the    sine    of   the
instantaneous phase.

Note that  conventional
linear  sweeps  may  be
generated  by   setting
the   "power"   (n)  to
zero.


?wavelet
WAVELET

Create   a  Zero-phase,
Butterworth  or  Ricker
Šwavelet

WAVELET    <b> 
<sample rate>  <length>
<type>    <parameter 1>
<parameter 2>

<b>   Output   register
(single    trace)    to
contain        computed
wavelet

<sample  rate>
Sample rate of wavelet

<length>
Length (ms.) of wavelet
to be generated

<Type>  Z  Zero Phase
        B  Butterworth
        R  Ricker

<parameters>
Depending on <Type> the
parameters are:

Z
F1, F2, F3,  F4
4 frequencies defining
an   Ormsby   bandpass
filter.

B
LF, HF, LO, HO
Low   frequency  (LF),
High   frequency  (HF)
corresponding  to  the
3db points.  LO and HO
are  the low and  high
order    (number    of
poles).

R
F
Dominant frequency
(.Hz.)

Examples:
WAVE a
2 100 Z 10 20 70 80

WAVE a
2 100 B 20 80  2  2

ŠWAVE a
2 100 R 40

The  specified  wavelet
will be calculated  and
placed  in  the  output
register        (single
trace).     The   clock
shows  the  computation
sample by sample.


?wiener_inverse
WIENER

Wiener filter from auto
and  cross  correlation
functions

WIEN <a>  and  <b> put
<c> <prewh>

<a> Input
autocorrelation
function -  the values
.S 0.5
r , r , r  etc.
 0   1   2
.S 1.0

as shown in the matrix
equation below.

<b>  Cross correlation
function of  the input
and    some    desired
output the values
.S 0.5
g ,g , g  etc as shown
 0  1   2
.S 1.0

below.


<c>    Output
filter  - the values
.S 0.5
f ,f ,f  etc. below
 0  1  2
.S 1.0


<prewh>
Pre-whitening factor
.S 0.5
to  be  applied to r -
                    0
.S 1.0

first sample of the
input auto-correlation

ŠThis command allows the
user   to  perform  the
classical       Wiener-
Levinson     recursion.
The  set  up  for  this
command  will doubtless
be quite lengthy as the
inputs   involve    the
computation of auto and
cross correlations.

The   actual  algorithm
solved      is      the
following:

Rf  =  g
R   =  autocorrelation
       matrix
f   =  filter
       coefficients
g   =  cross-corr of
       input with
       desired output.

Obviously   the   input
registers  must  be the
same    length,    same
sample   rate   and  at
present  must  also  be
single   trace.     The
output filter takes its
length and sample  rate
from the input.


?window_zone
WINDOW

Set a window for future
references     to     a
register

WINDOW <a> <start time>
<end time>

<a> Input register

<start time>
    start of window(ms)

<end time>
    End of window(ms)

Example:  WINDOW a  500
          700
Š
Following this command,
all future  uses of the
specified  register  as
an   input    to   some
operation,   will  only
use  the   data   lying
within    the     given
window.


?zap_all_registers
ZAP

Zero all registers

ZAP

This    command    will
re-initialize       all
registers to zero.
