[Octave-bug-tracker] [bug #51779] bsxfun unit tests occasionally fail on certain random inputs

[Mike Miller]

Update of bug #51779 (project octave):

                  Status:                    None => Confirmed              

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Follow-up Comment #4:

This regression was introduced with

https://hg.savannah.gnu.org/hgweb/octave/rev/b488e958d024

Use modf, pow from C++ std library. These functions are guaranteed to be part
of C++11 standard library.

Something about this has changed the following two operations, compared to
Octave 4.2.1:


power (single ([-0.0226; 0]), int32 ([-5 0]))
single ([-0.0226; 0]) .^ int32 ([-5 0])


This has something to do with the mixed types and the broadcasting expansion.
This does not affect the normal elementwise exponentiation when both operands
have the same dimension. And calling bsxfun explicitly is also not affected.

This is possibly because the change is now calling std::pow, which is a
function template, so different underlying C functions might be called. Before
this change, these few spots in the code were calling the C function pow,
which always takes its arguments as doubles.

I may try forcing some of these std::pow calls to operate on doubles to see if
anything has an effect by trial and error.

Adding Rik in cc.

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