nf_Legendre_GaussianQuadrature.cc File Reference

#include "nf_Legendre.h"

Go to the source code of this file.

Classes
struct	nf_Legendre_GaussianQuadrature_degree

Macros
#define	n_3   3
#define	n_4   4
#define	n_5   5
#define	n_10   10
#define	n_20   20
#define	n_40   40
#define	nSets   6

Functions
nfu_status	nf_Legendre_GaussianQuadrature (int degree, double x1, double x2, nf_Legendre_GaussianQuadrature_callback func, void *argList, double *integral)

Macro Definition Documentation

n_10

#define n_10   10

Definition at line 33 of file nf_Legendre_GaussianQuadrature.cc.

n_20

#define n_20   20

Definition at line 37 of file nf_Legendre_GaussianQuadrature.cc.

n_3

#define n_3   3

Definition at line 21 of file nf_Legendre_GaussianQuadrature.cc.

n_4

#define n_4   4

Definition at line 25 of file nf_Legendre_GaussianQuadrature.cc.

n_40

#define n_40   40

Definition at line 45 of file nf_Legendre_GaussianQuadrature.cc.

n_5

#define n_5   5

Definition at line 29 of file nf_Legendre_GaussianQuadrature.cc.

nSets

#define nSets   6

Definition at line 57 of file nf_Legendre_GaussianQuadrature.cc.

Function Documentation

nf_Legendre_GaussianQuadrature()

nfu_status nf_Legendre_GaussianQuadrature	(	int	degree,
		double	x1,
		double	x2,
		nf_Legendre_GaussianQuadrature_callback	func,
		void *	argList,
		double *	integral
	)

Definition at line 63 of file nf_Legendre_GaussianQuadrature.cc.

                                                                                                                                                             {
 
    int i, n;
    double x, mu, sum, *weights, *xis;
    nfu_status status = nfu_Okay;
 
    *integral = 0;
    if( degree < 2 ) {
        status = func( 0.5 * ( x1 + x2 ), integral, argList );
        *integral *= 2.; }
    else if( degree < 4 ) {
        x = 0.5 * ( -sqrt_inv3 * ( x2 - x1 ) + x1 + x2 );
        if( ( status = func( x, integral, argList ) ) == nfu_Okay ) {
            x = 0.5 * (  sqrt_inv3 * ( x2 - x1 ) + x1 + x2 );
            status = func( x, &sum, argList );
            *integral += sum;
        } }
    else {
        for( i = 0; i < nSets - 1; i++ ) {
            if( GaussianQuadrature_degrees[i].n > ( degree + 1 ) / 2 ) break;
        }
        n = ( GaussianQuadrature_degrees[i].n + 1 ) / 2;
        weights = GaussianQuadrature_degrees[i].weights;
        xis = GaussianQuadrature_degrees[i].xis;
        for( i = 0; i < n; i++ ) {
            mu = xis[i];
            x = 0.5 * ( x1 * ( 1 - mu ) + x2 * ( mu + 1 ) );
            if( ( status = func( x, &sum, argList ) ) != nfu_Okay ) break;
            *integral += sum * weights[i];
            if( mu == 0 ) continue;
            x = x1 + x2 - x;
            if( ( status = func( x, &sum, argList ) ) != nfu_Okay ) break;
            *integral += sum * weights[i];
        }
    }
    *integral *= 0.5 * ( x2 - x1 );
    return( status );
}

Referenced by nf_Legendre_from_ptwXY().