PyCRlibm - Python bindings for CRlibm

Travis CI build status (Linux) AppVeyor CI build status (Windows) Latest PyPI version Documentation Status

Python bindings for CRlibm, an efficient and proven correctly-rounded mathematical library.

CRlibm is a free mathematical library (libm) which provides:

  • implementations of the double-precision C99 standard elementary functions,
  • correctly rounded in the four IEEE-754 rounding modes,
  • with a comprehensive proof of both the algorithms used and their implementation,
  • sufficiently efficient in average time, worst-case time, and memory consumption to replace existing libms transparently.


At the command line:

$ pip install crlibm

On Microsoft Windows pip will try first to download a binary archive in wheel format, and if no such a wheel can be found for your Python version, pip will try to compile the library. In order to do so, it is strongly recommended to have MinGW-w64 installed under MSYS2, for instance by following the instructions in


In Python:

>>> import crlibm
>>> crlibm.exp_ru(1)

>>> crlibm.exp_rd(1)


  • This project provides the bindings for the functions in the following table:
f(x) Round to nearest Round up (to +∞) Round down (to -∞) Round to 0
Exponentials and logarithms
exp(x) exp_rn exp_ru exp_rd exp_rz
exp(x)-1 expm1_rn expm1_ru expm1_rd expm1_rz
log(x) log_rn log_ru log_rd log_rz
log(1+x) log1p_rn log1p_ru log1p_rd log1p_rz
log(x)/log(2) log2_rn log2_ru log2_rd log2_rz
log(x)/log(10) log10_rn log10_ru log10_rd log10_rz
sinh(x) sinh_rn sinh_ru sinh_rd sinh_rz
cosh(x) cosh_rn cosh_ru cosh_rd cosh_rz
sin(x) sin_rn sin_ru sin_rd sin_rz
cos(x) cos_rn cos_ru cos_rd cos_rz
tan(x) tan_rn tan_ru tan_rd tan_rz
asin(x) asin_rn asin_ru asin_rd asin_rz
acos(x) acos_rn acos_ru acos_rd acos_rz
atan(x) atan_rn atan_ru atan_rd atan_rz
Trigonometry in multiples of π
sin(π * x) sinpi_rn sinpi_ru sinpi_rd sinpi_rz
cos(π * x) cospi_rn cospi_ru cospi_rd cospi_rz
tan(π * x) tanpi_rn tanpi_ru tanpi_rd tanpi_rz
asin(x)/π asinpi_rn asinpi_ru asinpi_rd asinpi_rz
acos(x)/π acospi_rn acospi_ru acospi_rd acospi_rz
atan(x)/π atanpi_rn atanpi_ru atanpi_rd atanpi_rz
  • The function pow in CRlibm is not exported.


Both the CRlibm library and the Python bindings are distributed under the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.


David Defour, Catherine Daramy, Florent de Dinechin, Matthieu Gallet, Nicolas Gast, Christoph Lauter, Jean-Michel Muller.

Python bindings by Stefano Taschini.