fill in matrix element from another element in same matrix

[relayman357]

I'm building a matrix where the off-diagonals are equal (e.g. M(1,3) = M(3,1) etc.).   Is there a way to reference the M(1,3) to populate the M(3,1) element?

That way I would just need to populate the diagonal and upper triangle and below the diagonal would be completed.

thanks,

russ

[Werner_E]

A tiny user-defined function may do the job:

[LucMeekes · Accepted solution]

My two cents:

Success!
Luc