Révision 51 pobysoPythonSage/src/sageMpfr.spyx
| sageMpfr.spyx (revision 51) | ||
|---|---|---|
| 1 | 1 |
from sage.rings.real_mpfr cimport * |
| 2 | 2 |
# |
| 3 |
# Two functions to manipulate the real RealNumber values.
|
|
| 3 |
# Functions to manipulate the real RealNumber values.
|
|
| 4 | 4 |
# |
| 5 |
# Get the address of the value of a RealNumber. This address can be |
|
| 6 |
# used to to set the value as well. |
|
| 7 |
# |
|
| 5 |
# Import constants and declarations that are not exported |
|
| 6 |
# from the Sage real_mpfr.pyx file. |
|
| 7 |
# Notes: |
|
| 8 |
# - notice how #define constants are imported. |
|
| 9 |
# - mpfr_min_prec is declared with an int return value, not |
|
| 10 |
# a mpfr_prec_t since it is not recognized as type in Cython. |
|
| 11 |
cdef extern from "mpfr.h": |
|
| 12 |
cdef int MPFR_PREC_MIN "MPFR_PREC_MIN" |
|
| 13 |
cdef int mpfr_min_prec(mpfr_t x) |
|
| 14 |
|
|
| 15 |
|
|
| 8 | 16 |
cpdef int get_rn_value(RealNumber x): |
| 17 |
""" |
|
| 18 |
Get the address of the value of a RealNumber. This address can be |
|
| 19 |
used to to set the value as well. |
|
| 20 |
""" |
|
| 9 | 21 |
return(<int>&(x.value)) |
| 10 |
# |
|
| 11 |
# We use the "array trick" to workaround the pointer dereferencing |
|
| 12 |
# issue (in Cython there is no unary operator "*"). |
|
| 13 |
# |
|
| 22 |
|
|
| 14 | 23 |
cpdef set_rn_value(RealNumber x, int p, mp_rnd_t rnd=GMP_RNDN): |
| 24 |
""" |
|
| 25 |
Set the value of x from MPFR number p. |
|
| 26 |
""" |
|
| 27 |
# We use the "array trick" to workaround the pointer dereferencing |
|
| 28 |
# issue (in Cython there is no unary operator "*"). |
|
| 29 |
# |
|
| 15 | 30 |
mpfr_set(x.value, (<mpfr_t *>p)[0], rnd) |
| 16 | 31 |
# |
| 32 |
cpdef min_rn_size(RealNumber x): |
|
| 33 |
""" |
|
| 34 |
Compute the minimum number of bits necessary to represent |
|
| 35 |
a RealNumber's value. |
|
| 36 |
If x is a power of 2 (only 1 bit needed) return the MPFR |
|
| 37 |
MPFR_PREC_MIN value. |
|
| 38 |
""" |
|
| 39 |
cdef int min_prec = mpfr_min_prec(x.value) |
|
| 40 |
if min_prec < MPFR_PREC_MIN: |
|
| 41 |
return(MPFR_PREC_MIN) |
|
| 42 |
else: |
|
| 43 |
return(min_prec) |
|
| 44 |
|
|
| 17 | 45 |
# Do not use this function! |
| 18 | 46 |
# It changes the precision of the instance behind the curtain, but precision is |
| 19 | 47 |
# class attribute. If the precision is increased, memory space is wasted and |
Formats disponibles : Unified diff