SciPy

darkhistory.utilities.exp_expn

darkhistory.utilities.exp_expn(n, x)

Returns \(e^x E_n(x)\).

The exponential integral \(E_n(x)\) is defined as

\[E_n(x) \equiv \int_1^\infty dt\, \frac{e^{-xt}}{t^n}\]

Circumvents overflow error in np.exp by expanding the exponential integral in a series to the 5th or 6th order.

Parameters:
n : {1,2}

The order of the exponential integral.

x : ndarray

The argument of the function.

Returns:
ndarray

The value of \(e^x E_n(x)\).

Previous topic

darkhistory.utilities.compare_arr

Next topic

darkhistory.utilities.get_grid

This Page