my problem is somewhat hard to pin down, since I notice it only on a fairly high level in the code. In the code I am developing, a number of matrix operations are performed using the Numerical Recipes routines. ifc gives erroneous and internally inconsistent results for singular value decomposition and for Cholesky decomposition of my positive-definite symmetric matrix. The operations occasionally do involve the evaluation of differences between nearly equal numbers, but nowhere do these get close to machine precision.
I compared the test results with those obtained with the Portland Group Fortran compiler (which is twice as slow; hats off for to you for speed!). This compiler does produce the correct result from the same code.
I would be happy to supply more details of the problem if anyone has a clue where to look.
ifc gives wrong result in matrix analysis