Running Fortran 90 code on SGI, I sometimes get the following message: PSLDLT Error: Index out of range (-1) and the program execution terminates. Can anyone familiar with this error explain me what is it? Thanks

Thats simple. You probably have some arrays and you are exceeding the array limits, i.e., going below IMIN which is usually 1, or going above IMAX.

Thanks, Praveen. That doesn't seem to be the problem because I am using dynamic memmory allocation for all the arrays and matrices. Or, you mean some other thing! -Malik

Its not a problem with memory allocation. You are probably trying to access the array beyond its limits. This usually happens if you have some loop, look for things like

for i=1 to imax

and inside you might be trying to access array(i-1) or array(i+1)

endfor

This can be quite a headache sometimes. If by mistake you try to access ARRAY(0) or ARRAY(imax+1) which are out of the range, then some compilers just dont give any warning. This is terrible because you wont even know that there is a mistake. I once discovered this problem while tring to run my code on SGI; it did not give any error on a linux pc. I think there are compilation flags which will check for array bounds. There is a flag -fbounds-check on g77. Check your man pages.