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Subject: Re: [boost] [ublas] bugfix for matrix operation /
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2013-04-16 23:16:57


On 04/16/2013 07:20 PM, Mario Mulansky wrote:
> Hi,
> I wanted to add an elementwise divide operations for ublas matrices using
> operator /

I don't think that's such a great idea.
Using regular operators for elementwise
operations is likely to be surprising.
i.e. if you can do (A / B) you should
be able to do (A * B) as well, and it
you be the inverse of A / B. But
multiplication is defined for matrices
and is *not* an elementwise operation.
There is no way to define this that
won't surprise someone. There's a
good reason why uBlas doesn't provide
these operators already and why MATLAB
has a separate set of operators for
elementwise operations.

> Unfortunately, there is operator/ defined for matrix and integral types which
> hides any other operator definition (matrix_expression.hpp l. 3388) and thus
> makes it impossible to add this functionality. I would like to add an
> enable_if statement there that checks if the second argument is convertible to
> matrix::value_type, as is done for other operators. Who would be responsible
> for this small change? I can provide the according patch, it's almost trivial.

In Christ,
Steven Watanabe

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