Indeed, instead of ignoring the `check` keyword altogether over inexact fields, it would be useful to verify the solution when that is possible, such as for exact input over SR and for ball and intervall fields. I have opened #29729 <https://trac.sagemath.org/ticket/29729> for this. For general inexact rings though, the result cannot be verified, so it would not make sense to do the check by default.
Am Samstag, 23. Mai 2020 07:15:45 UTC+2 schrieb Dave Morris: > > From the documentation at > https://www.mathworks.com/help/matlab/ref/mldivide.html, it appears to me > that MATLAB gives a warning: "Warning: Matrix is close to singular or badly > scaled. Results may be inaccurate." That seems to me to be a better > default behavior than what sage is doing now, but I think it would make > sense to let users choose to turn off the warning (and maybe also let them > upgrade it to an error). > The generic implementation of `solve_right` does not provide this. I would suggest to use a type that has a specialized implementation for this, such as RDF, CDF, CBF. For example over RDF and CDF, a warning is issued if the input is ill-conditioned and an error is raised if the matrix is singular, which is a reasonable behavior: sage: matrix(RDF, [[2/3, 1], [0.4, 0.6]]).solve_right(vector(RDF, [1, 1])) /Applications/SageMath/src/bin/sage-ipython:1: LinAlgWarning: Ill-conditioned matrix (rcond=2.77556e-17): result may not be accurate. #!/usr/bin/env sage-python (5404319552844596.0, -3602879701896396.0) sage: matrix(RDF, [[0]]).solve_right(vector(RDF, [1])) ... LinAlgError: Matrix is singular. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/bf5e377d-630c-49f9-8347-4798dd6fd8bc%40googlegroups.com.
