ASKSAGE: Sage Q&A Forum - Individual question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 20 Dec 2017 04:55:01 -0600Is there a way do declare a python function or fast_callable fo a cython function ?http://ask.sagemath.org/question/40252/is-there-a-way-do-declare-a-python-function-or-fast_callable-fo-a-cython-function/I want to get efficient code for a repetitive computation on a "grid" of arguments, using a runtime-defined function (passed as an argument). Basically :
def myfunc(f, somerange, someotherrange):
initstorage()
for x in somerange:
for y in someotherrange:
store(x,y,dosomething(f,x,y))
return storage
In order to accelerate things, I'd like to write myfunc in cython.
I can safely assume that my numerical arguments (`x ` and `y`) will be coerced to double, so I can further accelerate things gy declaring them as typed. The problem is the function argument `f`. I can test the nature of `f` (e. g. before `initstorage()` and set `dosomething` to a special_case function according to this nature.
There are basically four cases :
* a symbolic expression : it seems that, in most cases, it pays to generate a `fast_callable`.
* a `fast_callable`.
* a Python function or a lambda expression.
* a Cython function declared as `cpdef`, or a C/C++ function suitably imported.
For this last case, I know the solution : it is enough to declare the relevant function signature with `ctypedef`, and use this type in the declaration of my function :
ctypedef double (*mytype)(double, double)
and use it to declare `myfunc` :
cpdef myfunc(mytype, double, double): #see above...
with the benefit of acceleration due to static typing.
Can something analogous be done in the three other cases (or possibly in the `fast_callable` and Python function cases, an expression being convertible to the `fast_callable` case) ?Wed, 20 Dec 2017 04:55:01 -0600http://ask.sagemath.org/question/40252/is-there-a-way-do-declare-a-python-function-or-fast_callable-fo-a-cython-function/