expInt1 Module Function

elemental module function expInt1(val) result(res)

Allan and Hastings approximation of E1 exponential integral, with coefficients from routine in: Shanjie Zhang, Jianming Jin, Computation of Special Functions, Wiley, 1996, ISBN: 0-471-11963-6, LC: QA351.C45.

Arguments

Type IntentOptional Attributes Name
real(kind=rk), intent(in) :: val

Return Value real(kind=rk)