The norm flag causes the sum to be divided by the number of files. The sum is carried as a 32 bit integer, so clipping should not be a problem until the file is written.
If a box is specified, then the operations are only carried out over the box.
The number of rows and columns in file1 must equal to those in file2.
The result is placed in file1 unless the outfile= option is specified.
add alflyr gamma - adds the file gamma to the file alflyr
add alflyr const=45 - adds 45 to the file alflyr
add gamma1 gamma2 gamma3 norm -adds files gamma2 and gamma3 to gamma1 and
divides the result by
3.