Am Mittwoch, 9. Juli 2014 16:18:03 UTC+2 schrieb Volker Braun:
>
> Python/Cython classes are not C++ classes, so you can't call Py/Cy methods
> from C++ code directly. It can of course be done using the CPython C API or
> Boost.Python, but a Python object is never a straight C++ object. For
> starters it doesn't have a C++ vtable, methods can be added dynamically in
> Python...
>
> The two basic patterns for Cython code are
>
> A) Write your implementation in Python first. Then switch py->pyx Cython.
> Then identify the slow parts and cdef variables & methods as appropriate,
> so that Cython can generate fast C code instead of having to call the
> CPython API always.
>
> B) Write your implementation in C++ first, or use an existing code. Wrap
> the C++ objects in Cython objects (
> http://docs.cython.org/src/userguide/wrapping_CPlusPlus.html). In this
> case you'd want to pass the raw matrix data as a pointer.
>
>
Thank you for your response.
I am trying to go with option B, that is one of the reasons I looked at
linbox code.
One of the main points of my project is, that there are already wrappers
for the objects I want to use (NTLs ZZ_pEX and GF2EX are already wrapped,
see sage.rings.polynomial.
polynomial_zz_pex.Polynomial_ZZ_pEX), and there are matrix types defined
and wrapped. When I looked at linbox code (example used: echelon-form) I
found the following code:
int rowReducedEchelon(Matrix &E, const Matrix& A)
They use references for Matrices throughout the file.
These functions are specified in echelon-form.pxd
cdef extern from "linbox/algorithms/echelon-form.h":
cdef cppclass EchelonFormDomainDouble
"LinBox::EchelonFormDomain<LinBox::Modular<double>
>":
EchelonFormDomainDouble(ModDoubleField)
int rowReducedEchelon(BlasMatrixDouble, BlasMatrixDouble)
The objects I want to use are most likely already wrapped somewhere in sage
(NTL for example is a c++ library, the matrix representation I do not know
at all, that is one of the problems).
So it shouldn't be necessary to build my own objects and wrap them, or at
least I thought so. And if I have to build my own wrappers, I'd have to
make them compatible with sage internal objects, but I think that would be
easier, as both are defined in cython.
Regards,
David
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