Why am I getting incorrect 1 sigma results (NaN) from a correlated
PSD analysis in ANSYS 8.1?
You have negative numbers in your correlation input.
This is not being handled correctly and is fixed by Defect 24621.
A temporary workaround is use the old, undocumented numerical
/nerr,,,-1 ! do not exit on integration error messages
spopt,psd,,yes,,,6,500,NUME ! use numerical integration of psd tables