[Octave-bug-tracker] [bug #33503] null.m: tolerance for zero in basis elements

[Olaf Till]

Follow-up Comment #15, bug #33503 (project octave):

Probably Jordy was meant, not me (and currently I have no Matlab access), but
a comment: You are right that the numerical problems are principally similar
to guessing, given sin(x), whether x may be a multiple of pi. But while I see
no use for the latter, there can be a special interest in guessing whether
some elements of the basis of the null space of a matrix could be zero (since
their being zero can mean that some elements of certain solutions involving
this matrix are defined; I struck this problem in computing the defined
elements of the covariance matrix of parameters after optimization). And the
previous code did already apply a tolerance, just for this purpose (to guess
if elements could be zero), only the wrong tolerance.

Maybe I can check with Matlab in the next days, I'll see.

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