FARITH - File ARITHmetic -- perform simple arithmetic with binary files

farith <infile >outfile [optional parameters]

Optional Parameters:
in=stdin input file
out=stdout output file
in2= second input file (required for binary operations)
if it can't be opened as a file, it might be a scalar
n=size_of_in, fastest dimension (used only for op=cartprod is set)
isig= index at which signum function acts (used only for
op=signum)
op=noop noop for out = in
neg for out = -in
abs for out = abs(in)
scale=1 for out = in * scale
exp for out = exp(in)
log for out = log(in)
sqrt for out = (signed) sqrt(in)
sqr for out = in*in
pinv for out = (punctuated) 1 / in
pinvsqr for out = (punctuated) 1 /in*in
pinvsqrt for out = (punctuated signed) 1 /sqrt(in)
add for out = in + in2
sub for out = in - in2
mul for out = in * in2
div for out = in / in2
cartprod for out = in x in2
requires: n=size_of_in, fastest dimension in output
signum for out[i] = in[i] for i< isig and
= -in[i] for i>= isig
requires: isig=point where signum function acts
Seismic operations:
slowp for out = 1/in - 1/in2 Slowness perturbation
slothp for out = 1/in^2 - 1/in2^2 Sloth perturbation

Notes:
op=sqrt takes sqrt(x) for x>=0 and -sqrt(ABS(x)) for x<0 (signed sqrt)

op=pinv takes y=1/x for x!=0, if x=0 then y=0. (punctuated inverse)

The seismic operations assume that in and in2 are wavespeed profiles.
"Slowness" is 1/wavespeed and "sloth" is 1/wavespeed^2.
Use "suop" and "suop2" to perform unary and binary operations on
data in the SU (SEGY trace) format.

The options "pinvsq" and "pinvsqrt" are also useful for seismic
computations involving converting velocity to sloth and vice versa.

The option "cartprod" (cartesian product) requires also that the
parameter n=size_of_in be set. This will be the fastest dimension
of the rectangular array that is output.

The option "signum" causes a flip in sign for all values with index
greater than "isig" (really -1*signum(index)).



AUTHOR: Dave Hale, Colorado School of Mines, 07/07/89
Zhaobo Meng added scale and cartprod, 10/01/96
Zhaobo Meng added signum, 9 May 1997
Tony Kocurko added scalar operations, August 1997