topic incomplete gamma function in Intel® oneAPI Math Kernel Library

incomplete gamma function

Gabriella_Petaccia — Thu, 08 Mar 2012 17:25:17 GMT

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

incomplete gamma function

mecej4 — Thu, 08 Mar 2012 17:52:55 GMT

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).

incomplete gamma function

Bernard — Thu, 31 May 2012 17:28:23 GMT

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]

incomplete gamma function

rudi-gaelzer — Fri, 01 Jun 2012 16:37:13 GMT

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.