Have py_scalar_to_element convert gmpy2 numbers

[vklein]

Currently py_scalar_to_element function (coerce.pyx) doesn't convert gmpy2 numbers. py_scalar_to_element should work with gmpy2 the same way it does with numpy.

[vklein]

New commits:

​8555214

Trac #25128: ``gmpy2``'s types and ``py_scalar_to_element``

[vdelecroix]

You have C functions for type checking: MPZ_Check, MPQ_Check, MPFR_Check and MPC_Check.

[vdelecroix]

(this is the kind of things that are of course not optimized by Cython)

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​c3a55ec

Trac #25128: Change ``gmpy2``'s type checking with ...

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​95da017

Trac #25128: Change ``gmpy2``'s type checking with ...

[vdelecroix]

There needs to be a linebreak after ::

+    Test gmpy2's types::
+        sage: import gmpy2                               # optional - gmpy2 

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​783c01d

Trac #25128: Fix missing linebreak after ``::``

[vklein]

Fix missing linebreak.

[jdemeyer]

Why MPZ_Check(x) instead of type(x) is gmpy2.mpz? There is nothing really wrong with MPZ_Check but all other places in Sage use the type check. For example in src/sage/rings/complex_double.pyx:

if HAVE_GMPY2 and type(x) is gmpy2.mpc:

If you use only type checks, you can also remove the import_gmpy2.

[jdemeyer]

I just benchmarked it and MPZ_Check() is slightly slower than the type() check. This is probably because the import_gmpy2 machinery gives a slight overhead compared to the direct import that Cython does.

[vklein]

Ok i will reverse to type() check then. I see no reason to keep MPZ_Check() if it's not faster.

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​ff11b13

Trac #25128: ``gmpy2``'s types and ``py_scalar_to_element``

[vklein]

previous commits squashed.

[jdemeyer]

Fine for me but I leave the final review to Vincent Delecroix.

[vdelecroix]

Sure it's fine.