[Numpy-discussion] Which dtype are supported by numexpr ?

Francesc Altet faltet@carabos....
Fri Mar 9 11:56:28 CST 2007


A Divendres 09 Març 2007 18:40, Sebastian Haase escrigué:
> Hi !
> This is really only one question:
>
> Which dtypes are supported by numexpr ?

Well, numexpr does support any dtype that is homogeneous, except 'uint64'. 
This is because internally all the unsigned types are upcasted to the 
smallest *signed* integer that can fit the info for it. As it happens 
that 'uint64' doesn't have a standard signed type above that is able to keep 
its info: this is why it is unsupported.

Besides, there is the limitation that Win32 doesn't have such a 'uint64', and 
computations in numpy or python are normally done by converting them to 
python long integers (correct me if I'm wrong here), whose arithmetic is very 
slow compared with the types supported by the compiler.  So, the best 
approach is to avoid 'uint64' types in general.

> We are very interested in numexpr !
> Where is the latest / most-up-to-date documentation ?

At the moment, I think documentation is reduced at some docstrings. If you 
want more, you will have to look at the sources.

HTH,

-- 
>0,0<   Francesc Altet     http://www.carabos.com/
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