FARITH - File ARITHmetic -- perform simple arithmetic with binary files farith 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) scale= value to scale in by, used only for op=scale) bias= value to bias in by, used only for op=bias) op=noop noop for out = in neg for out = -in abs for out = abs(in) scale for out = in *scale bias for out = in + bias 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)). For file operations on SU format files, please use: suop, suop2 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 John Stockwell added bias option 4 August 2004