fix error messages for MatProduct
Fix error message when MatProductSymbolic() is not supported for the matrix types or MatProductSetFromOptions() is not called
Reported-by: Hana Honnerová hhornik@kma.zcu.cz
Edited by Hong Zhang
Fix error message when MatProductSymbolic() is not supported for the matrix types or MatProductSetFromOptions() is not called
Reported-by: Hana Honnerová hhornik@kma.zcu.cz