Public Member Functions | |
| real(kind=wp) function | wp_gamic (A, X) |
| DECK wp_gamic ***BEGIN PROLOGUE wp_gamic ***PURPOSE Calculate the complementary incomplete Gamma function. ***LIBRARY SLATEC (FNLIB) ***CATEGORY C7E ***TYPE REAL(kind=wp) (GAMIC-S, wp_gamic-D) ***KEYWORDS COMPLEMENTARY INCOMPLETE GAMMA FUNCTION, FNLIB, SPECIAL FUNCTIONS ***AUTHOR Fullerton, W., (LANL) ***DESCRIPTION. More... | |
| real(kind=ep1) function | ep_gamic (A, X) |
| Quad precision version of wp_gamic. More... | |
Member Function/Subroutine Documentation
◆ ep_gamic()
| real(kind=ep1) function special_functions_gbl::cfp_gamic::ep_gamic | ( | real(kind=ep1) | A, |
| real(kind=ep1) | X | ||
| ) |
Quad precision version of wp_gamic.
◆ wp_gamic()
| real(kind=wp) function special_functions_gbl::cfp_gamic::wp_gamic | ( | real(kind=wp) | A, |
| real(kind=wp) | X | ||
| ) |
DECK wp_gamic ***BEGIN PROLOGUE wp_gamic ***PURPOSE Calculate the complementary incomplete Gamma function. ***LIBRARY SLATEC (FNLIB) ***CATEGORY C7E ***TYPE REAL(kind=wp) (GAMIC-S, wp_gamic-D) ***KEYWORDS COMPLEMENTARY INCOMPLETE GAMMA FUNCTION, FNLIB, SPECIAL FUNCTIONS ***AUTHOR Fullerton, W., (LANL) ***DESCRIPTION.
Evaluate the complementary incomplete Gamma function
wp_gamic = integral from X to infinity of EXP(-T) * T**(A-1.) .
wp_gamic is evaluated for arbitrary real values of A and for non- negative values of X (even though wp_gamic is defined for X .LT. 0.0), except that for X = 0 and A .LE. 0.0, wp_gamic is undefined.
wp_gamic, A, and X are REAL(kind=wp).
A slight deterioration of 2 or 3 digits accuracy will occur when wp_gamic is very large or very small in absolute value, because log- arithmic variables are used. Also, if the parameter A is very close to a negative INTEGER (but not a negative integer), there is a loss of accuracy, which is reported if the result is less than half machine precision.
***REFERENCES W. Gautschi, A computational procedure for incomplete gamma functions, ACM Transactions on Mathematical Software 5, 4 (December 1979), pp. 466-481. W. Gautschi, Incomplete gamma functions, Algorithm 542, ACM Transactions on Mathematical Software 5, 4 (December 1979), pp. 482-489. ***ROUTINES CALLED F1MACH, cfp_9gmic, cfp_9gmit, cfp_9lgic, cfp_9lgit, cfp_lgams, cfp_lngam, XERCLR, XERMSG ***REVISION HISTORY (YYMMDD) 770701 DATE WRITTEN 890531 Changed all specific intrinsics to generic. (WRB) 890531 REVISION DATE from Version 3.2 891214 Prologue converted to Version 4.0 format. (BAB) 900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ) 920528 DESCRIPTION and REFERENCES sections revised. (WRB) ***END PROLOGUE wp_gamic
The documentation for this interface was generated from the following file:
- /home/jacob/Work/codes/UKRmol/gitlab/ukrmol-in/source/gbtolib/source/special_functions.f90
