iprint: Controls the amount of output, as follows:
iprint = 1: The values of the average relative, average absolute, largest relative, and largest absolute differences are printed
iprint = 2: All the S-matrix elements are printed followed by the values of the average relative, average absolute, largest relative, and largest absolute differences
thresh: All S-matrix elements smaller than thresh are ignored in the comparison. If thresh is a positive number (or zero), the comparison and the output involves the moduli of the S-matrix elements. If thresh is negative, the comparison and the output involve both the real and the imaginary parts of the S matrix.