Why does pagemldivide not give Singular Matrix warnings?

The new pagemldivide function in R2022a Prerelease (I think also in Parallel Computing Toolbox) doesn't give any Singular Matrix warnings. Why is that?

>> mldivide([1,0;0,0],[1;1])

Warning: Matrix is singular to working precision.

ans =

1

Inf

>> pagemldivide([1,0;0,0],[1;1])

ans =

1

Inf

Answer 1

[Kenneth Johnson]

Summary of response from Technical Support:

The 'help' for 'pagemldivide' states that the function never warns for ill-conditioned inputs. The reason for this design choice is performance. The computations needed to throw the warning could be nearly as expensive as the solve itself.

The optional second output argument of pagemldivide can be used to get the (multidimensional) reciprocal condition number, but this can seriously degrade runtime performance.

Answer 2

[Steven Lord]

Please send all questions or feedback about a Prerelease release to Technical Support rather than posting to MATLAB Answers.