#10249: c++ and %cython in the notebook
---------------------------+------------------------------------------------
Reporter: was | Owner: jason
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.6.1
Component: misc | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by was):
You could test this by pasting the following into a notebook cell:
{{{
open("/tmp/a.h",'w').write("""
struct Elt10 {
long a, b;
};
Elt10 operator+(Elt10 x, Elt10 y) {
Elt10 z;
z.a = x.a + y.a;
z.b = x.a + y.a;
return z;
}
void iadd(Elt10* x, Elt10 y) {
x->a = x->a + y.a;
x->b = x->b + y.b;
}
Elt10 operator*(Elt10 x, Elt10 y) {
Elt10 z;
z.a = x.a*y.a + x.b*y.b;
z.b = x.b*y.a + x.a*y.b + x.b*y.b;
return z;
}
""")
}}}
Then making another notebook cell and pasting the following in:
{{{
%cython
#clang c++
cdef extern from "stdlib.h":
long random()
cdef extern from "/tmp/a.h":
cdef cppclass Elt10:
long a, b
Elt10 operator+(Elt10 x, Elt10 y)
Elt10 operator*(Elt10 x, Elt10 y)
void iadd(Elt10* x, Elt10 y)
cdef class Vec4:
cdef Elt10* elements
cdef long n
def __cinit__(self, Py_ssize_t n):
# dynamic memory allocation on the heap
self.elements = <Elt10*>malloc(n*sizeof(Elt10))
self.n = n
def __dealloc__(self):
free(self.elements)
def randomize(self):
cdef Py_ssize_t m
for m in range(self.n):
self.elements[m].a = random(); self.elements[m].b = random()
def dot(self, Vec4 other not None):
cdef Elt10 ans, tmp
ans.a = 0; ans.b = 0
cdef Py_ssize_t m
# This is the part that gets very worrisome, since the code does
# not look easy to read. And it can easily get massively more
complicated
# when the arithmetic isn't so simple!
for m in range(self.n):
ans = ans + self.elements[m] * other.elements[m]
return ans.a, ans.b
}}}
Then in a third cell do:
{{{
v = Vec4(10^6); w = Vec4(10^6); v.randomize(); w.randomize()
v.dot(w)
}}}
OK, not exactly a minimal example :-)
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10249#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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