Intel® oneAPI Math Kernel Library
Ask questions and share information with other developers who use Intel® Math Kernel Library.

incomplete gamma function

Gabriella_Petaccia
Principiante
2.441 Visualizações
i have found the gamma function but NOT the incomplete gamma function. Is this function lacking in the intel fortran?it seems so strange!thanks gabriella
0 Kudos
3 Respostas
mecej4
Colaborador honorário III
2.441 Visualizações
It is not strange to find that an infrequently used special function is not part of the standard library.

There are scores of special functions that are not provided as standard intrinsic functions in Fortran or other programming languages. It is up to you to find a library such as IMSL, or source code from places such as the Netlib collection (the function you want is probably DGAMI).
Bernard
Contribuidor valorado I
2.441 Visualizações
Here is code written in java for IncGamma.This code uses my gamma stirling method if are you interested i can post the code.

[bash]public double IncGammaLow(double x,double a){ double sum = 0; double result = 0; if(x < 0.0f){ throw new IllegalArgumentException("arg x must be greater than 0 t" + x); }else if( a < 0.0f || a == 0.0f || a < 1.0f){ throw new IllegalArgumentException("arg a must be not less than 1.0 t" + a); }else{ double exp,gamma_arg,gamma,nom,denom,power,gamma2; long k; int i,j; double[]array = new double[32]; double run_value; k = -1; run_value = 0; for(i = 0;i = run_value; } for(j = 0;j; } exp = Math.exp(-x); power = Math.pow(x, a); gamma2 = this.GammaStirlingApprox(a); result = power*gamma2*exp*sum; } return result; }[/bash]

rudi-gaelzer
Novo colaborador I
2.441 Visualizações
Gabriella, here you'll find a code for the incomplete gamma function for complex arguments:
http://www.cmis.csiro.au/Alan_Miller/index.html
Just look up for the cincgam.f90 code.
Responder