Slightly faster exp_series and atan_taylor.
Slightly faster exp_series and atan_taylor.

Alwnikrotikz/mpmath,upiterbarg/mpmath,Alwnikrotikz/mpmath,thegooglecodearchive/mpmath,tectronics/mpmath,thegooglecodearchive/mpmath,upiterbarg/mpmath,tectronics/mpmath