[Numpy-discussion] Proposed Roadmap Overview

Sturla Molden sturla@molden...
Mon Feb 20 09:29:46 CST 2012


Den 20.02.2012 08:35, skrev Paul Anton Letnes:
> In the language wars, I have one question. Why is Fortran not being considered? Fortran already implements many of the features that we want in NumPy:

Yes ... but it does not make Fortran a systems programming language. 
Making NumPy is different from using it.

> - slicing and similar operations, at least some of the fancy indexing kind
> - element-wise array operations and function calls
> - array bounds-checking and other debugging aid (with debugging flags)

That is nice for numerical computing, but not really needed to make NumPy.


> - arrays that mentally map very well onto numpy arrays. To me, this spells +1 to ease of contribution, over some abstract C/C++ template

Mentally perhaps, but not binary. NumPy needs uniformly strided memory 
on the binary level. Fortran just gives this at the mental level. E.g. 
there is nothing that dictates a Fortran pointer has to be a view, the 
compiler is free to employ copy-in copy-out. In Fortran, a function call 
can invalidate a pointer.  One would therefore have to store the array 
in an array of integer*1, and use the intrinsic function transfer() to 
parse the contents into NumPy dtypes.

> - in newer standards it has some nontrivial mathematical functions: gamma, bessel, etc. that numpy lacks right now

That belongs to SciPy.


> - compilers that are good at optimizing for floating-point performance, because that's what Fortran is all about

Insanely good, but not when we start to do the (binary, not mentally) 
strided access that NumPy needs. (Not that C compilers would be any better.)



> - not Fortran as such, but BLAS and LAPACK are easily accessed by Fortran
> - possibly other numerical libraries that can be helpful
> - Fortran has, in its newer standards, thought of C interoperability. We could still keep bits of the code in C (or even C++?) if we'd like to, or perhaps f2py/Cython could do the wrapping.

Not f2py, as it depends on NumPy.

- some programmers know Fortran better than C++. Fortran is at least used by many science guys, like me.


That is a valid arguments. Fortran is also much easier to read and debug.


Sturla







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