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static typing of mpf variables in cython

asked 2013-05-15 18:02:42 -0600

anonymous user



I am a new user of cython. I was looking for the static typing of python's mpf type variables in cython for speed up.

For example:

python: N=10 static typing in cython: cdef int N=10

Now I'm looking for the equivalent for mpf variables:

python: from mpmath import mpf , N = mpf(10)

cython: ??? maybe sth like: 'cdef mpf_t N=10' but this doesn't work.

Thank you,

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answered 2013-05-15 21:04:07 -0600

updated 2013-05-15 23:40:44 -0600


It depends. You have the choice of using a Cython variable as follows

from sage.rings.real_mpfr cimport RealNumber
from sage.rings.real_mpfr import RR

cdef RealNumber my_number = RR(5.634)

Or you can use pure C as follows

cdef mpfr_t value
mpfr_init2(value, 53)
mpfr_set_flt(value, 5.364, MPFR_RNDN)

Anyway, in the latter case, it is not possible to write value = 5 because there is no cast from int to mpfr_t (those are C variables)!

It might help to have a look at how the real number are implemented in Sage in the files

  • $SAGE_ROOT/devel/sage-main/sage/rings/real_mpfr.pyx
  • $SAGE_ROOT/devel/sage-main/sage/rings/real_mpfr.pxd
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Asked: 2013-05-15 18:02:42 -0600

Seen: 9,116 times

Last updated: May 15 '13