exponential_integral_1( z )
The numerical exponential integral E1 of z in SageMath. Defined by
\[ E_1 (z) = \int_z^\infty du \: \frac{ e^{ -u } }{ u } \]Numerical alternative to exp_integral_e1 that uses the PARI library rather than mpmath.
Plot on the real axis:
Series expansion about unity:
Special values:
Related functions: exp_integral_e1
Function category: exponential integrals sagemath-docs