The COND function returns the condition number of an n by n real or complex array A by explicitly computing NORM(A)·NORM(A -1 ). If A is real and A -1 is invalid (due to the singularity of A or floating-point errors in the INVERT function), COND returns -1. If A is complex and A -1 is invalid (due to the singularity of A ), calling COND results in floating-point errors.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.