On Wed, Sep 10, 2014 at 10:52 AM, Pauli Virtanen <[email protected]> wrote:
> 09.09.2014, 22:52, Charles R Harris kirjoitti: > > 1. Should the operator accept array_like for one of the arguments? > > 2. Does it need to handle __numpy_ufunc__, or will > > __array_priority__ serve? > > I think the __matmul__ operator implementation should follow that of > __mul__. > > [clip] > > 3. Do we want PyArray_Matmul in the numpy API? > > 4. Should a matmul function be supplied by the multiarray module? > > > > If 3 and 4 are wanted, should they use the __numpy_ufunc__ machinery, or > > will __array_priority__ serve? > > dot() function deals with __numpy_ufunc__, and the matmul() function > should behave similarly. > > It seems dot() uses __array_priority__ for selection of output return > subclass, so matmul() probably needs do the same thing. > > > Note that the type number operators, __add__ and such, currently use > > __numpy_ufunc__ in combination with __array_priority__, this in addition > to > > the fact that they are by default using ufuncs that do the same. I'd > rather > > that the __*__ operators simply rely on __array_priority__. > > The whole business of __array_priority__ and __numpy_ufunc__ in the > binary ops is solely about when __<op>__ should yield the execution to > __r<op>__ of the other object. > > The rule of operation currently is: "__rmul__ before __numpy_ufunc__" > > If you remove the __numpy_ufunc__ handling, it becomes: "__rmul__ before > __numpy_ufunc__, except if array_priority happens to be smaller than > that of the other class and your class is not an ndarray subclass". > > The following binops also do not IIRC respect __array_priority__ in > preferring right-hand operand: > > - in-place operations > - comparisons > > One question here is whether it's possible to change the behavior of > __array_priority__ here at all, or whether changes are possible only in > the context of adding new attributes telling Numpy what to do. > > I was tempted to make it a generalized ufunc, which would take care of a lot of things, but there is a lot of overhead in those functions. Sounds like the easiest thing is to make it similar to dot, although having an inplace versions complicates the type selection a bit. Chuck
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