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 ```
cond.pro
```

in the ```
lib
```

subdirectory of the IDL distribution.