Problem 451. Is this matrix orthogonal?

Created by Bruce Raine in Community

Given a square matrix, a, determine whether it is orthogonal.

INPUT: a, a n x n matrix

OUTPUT: true or false

Solve

Last solution submitted on Jun 27, 2019

Alfonso Nieto-Castanon on 5 Mar 2012

perhaps you could these cases to avoid some non-general solutions... TEST1: x=sqrtm([2,1;1,1]); y_correct=false; TEST2: x=randn(3); y_correct=false;

Bruce Raine on 7 Mar 2012

Thanks for the suggestions. I have implemented both of the tests. Cheers.

Andrew Dobrovolc on 11 Sep 2017

I believe the test cases are wrong, I could not prove that a matrix from randn(3) is orthogonal.