[Octave-bug-tracker] [bug #31974] Interpreter fails to create complex numbers with Inf complex parts

[John W. Eaton]

Follow-up Comment #14, bug #31974 (project octave):

In mixed complex/real element-by-element operations (either explicit .*, ./,
etc., operations, or scalar by matrix operations) we can intercept the
operation and pretend that a complex value with 0 real part is a pure
imaginary number and skip the 0 * Inf operation.  This should be done in the
function that implements the operator.  This may appear to do the "right"
thing in some cases, but will be inconsistent with anything that doesn't use
our special functions for these mixed ops.  For example, I think the test you
want is


[Inf, 0] * [i, 0]


This operation should use the BLAS, so the Inf*i won't be subject to a
special definition of a mixed real by complex multiplication operator.

I'm not convinced this is something we should "fix", but if we do, and we are
doing it for Matlab compatibility, I think we need to determine exactly how
deeply this special case should be handled.  Should it just be done in the
operator function(s)?  Should we replace <complex> with our own class that has
the special cases?  Do we only have to change the behavior of multiplication
or also division?  Other operators?

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