calgo_385 Module

CALGO 385

Algorithm 385.

Procedures:

  • dei: Exponential integral

Author

Kathleen Paciorek

History

  • 1970-07-01 - Kathleen Paciorek
    • Original code.
  • 2006-10-04 - Kathleen Paciorek
  • 2025-05-26 - Rodrigo Castro (GitHub: rodpcastro)
    • Converted the code from F77 to F90 using TO_F90 by Alan Miller.
  • 2025-05-26 - Rodrigo Castro (GitHub: rodpcastro)
    • Fixed frac = q2(8) + x to frac = q2(8) / denm for x in the interval [6,12] according to the algorithm in the reference publication.
  • 2025-06-06 - Rodrigo Castro (GitHub: rodpcastro)
    • Replaced DOUBLE PRECISION by real(wp).
    • Replaced constant arrays initialized with DATA and stored with SAVE by parameter.

References

  1. Kathleen A. Paciorek. 1970. Algorithm 385: Exponential integral Ei(x). Commun. ACM 13, 7 (July 1970), 446–447. https://doi.org/10.1145/362686.362696

Uses

  • module~~calgo_385~~UsesGraph module~calgo_385 calgo_385 module~csf_kinds csf_kinds module~calgo_385->module~csf_kinds iso_fortran_env iso_fortran_env module~csf_kinds->iso_fortran_env

Used by

  • module~~calgo_385~~UsedByGraph module~calgo_385 calgo_385 module~csf_exponential_integral csf_exponential_integral module~csf_exponential_integral->module~calgo_385 module~csf csf module~csf->module~csf_exponential_integral

Functions

public function dei(x)

CALGO 385 Exponential integral .

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Arguments

Type IntentOptional Attributes Name
real(kind=wp), intent(in) :: x

x ≠ 0

Return Value real(kind=wp)