Gamma LAT: Reference Manual

lin_comb_cpx

NAME
lin_comb_cpx - Calculation of complex linear function of input data values (float complex).

SYNOPSIS
lin_comb_cpx <nfiles> <f1> <f2> ... <constant_r> <constant_i> <factor1_r> <factor1_i> <factor2_r> <factor2_i> ... <f_out> <width> [start] [nlines] [pixav_x] [pixav_y] [zero_flag]

<nfiles>	number of input data files
<f1>	1. input data file (float complex)
<f2>	2. input data file (float complex)
...	further input files (float complex)
<constant_r>	constant value (real part) to add to output
<constant_i>	constant value (imaginary part) to add to output
<factor1_r>	factor1 (real part) to multiply with f1
<factor1_i>	factor1 (imaginary part) to multiply with f1
<factor2_r>	factor2 (real part) to multiply with f2
<factor2_i>	factor2 (imaginary part) to multiply with f2
...	factors for further input files
<f_out>	output file (float complex)
<width>	number of samples/row
[start]	starting line (default=1)
[nlines]	number of lines to display (default: 0=to end of file)
[pixav_x]	number of pixels to average in range (default=1)
[pixav_y]	number of pixels to average in azimuth (default=1)
[zero_flag]	NULL value interpretation flag (default: 0 => 0.0 interpreted as missing value 1 => 0.0 interpreted as valid image value)

EXAMPLE
lin_comb_cpx 3 1825_1868.cc 1868_1911.cc 1911_1954.cc 0.0 0.0 2.0 0.0 0.0 1.0 2.0 2.0 cc_out.ras 2500 1 0 3 3 0

Generates a file of float based on the 3 input data files using the linear function:
output = 0.0 + 2.0 * (re(first file)) + 1.0i * (second file) + 2.0 * (third file).
Multi-looking in range and azimuth (3 looks in each direction) is performed.
0.0 in the input data files is interpreted as missing value; for pixels with missing values 0.0 is written to the output file.

DESCRIPTION
lin_comb allows to generate an image defined by a linear function of a number of input files of type float complex.

Values 0.0 of the input data files may either be interpreted as NULL values (zero_flag=0) or as valid data. In the case of an interpretation as NULL values 0.0 is written to the output file as soon as at least one of the input data files has NULL value for a pixel.

The calulation of a complex linear function may be of interest to compute decompositions from polarimetric data. Multi-looking in range and/or azimuth may be applied. An image sub-section may also be selected.

To calculate non-linear functions of a number of input data files the program lin_comb may be copied, modified to calculate the specific function, compiled, and used.

SEE ALSO
typedef_ISP.h lin_comb.