Is there a basic function that gets one half of a symmetrical matrix?

Title speaks for itself. I have done multiple pairwise t-tests and want to get one half of the p-value matrix to check for false discovery rate, and wondered if there was a simple way of getting one half of that symmetrical matrix.

Any help is much appreciated. Thank you!

Answer 1

[David Haydock]

triu(X)

[John D'Errico]

Or its conjoined twin, tril(X).

Answer 2

[Walter Roberson]

squareform()