Hi FORTRAN 90/95 Users: Want to know some efficient way of comparing two or more large size arrays in FORTRAN 90/95. Thanks

To be a little more specific: The arrays could be of different lengths and want to compare them for duplication. -Malik

Oh, they are integer arrays representing sets? You want to determine what integers appear in both arrays? If the range of possible values is known and reasonable, you can mask a bit-array. Otherwise, just sort the arrays.

Thanks Jed. Yes, I have integer arrays. The range is not known all the time. Comparison by sorting turns out to be very time consuming. Some other suggestion, please!

Keep the arrays sorted or partially sorted. If you don't sort, you end up with O(n^2) which is much worse. A radix sort shouldn't be that bad. Where do these arrays come from? How big are they? I assume you solve equations at some point? Or is this for mesh manipulation? Would a different data structure be better?