4.1 pygsl.const.m
Mathematical constants

from pygsl.const.m import *
print sqrt2*sqrt2

Prints 2.0.
Here comes the list:
Name GSL Name value
e M_E e
log2e M_LOG2E $ \log_2 e$
log10e M_LOG10E $ \log_{10} e$
sqrt2 M_SQRT2 $ \sqrt{2}$
sqrt1_2 M_SQRT1_2 $ \sqrt{1/2}$
sqrt3 M_SQRT3 $ \sqrt{3}$
pi M_PI $ \pi$
pi_2 M_PI_2 $ \pi/2$
pi_4 M_PI_4 $ \pi/4$
sqrtpi M_SQRTPI $ \sqrt{\pi}$
2_sqrtpi M_2_SQRTPI $ 2/\sqrt{\pi}$
1_pi M_1_PI $ 1/\pi$
2_pi M_2_PI $ 2/\pi$
ln10 M_LN10 $ \ln 10$
ln2 M_LN2 $ \ln 2$
lnpi M_LNPI $ \ln{\pi}$
euler M_EULER Euler constant