KmlIssCgSetUserPreconditioner?I

Associate with user-defined preconditioners for callback. This interface is not required if no user-defined preconditioner is used.

Interface Definition

C interfaces:

int KmlIssCgSetUserPreconditionerSI(KmlSolverTask **handle, void *ustruct, int (*fptr)(void *ustruct, float *x));

int KmlIssCgSetUserPreconditionerDI(KmlSolverTask **handle, void *ustruct, int (*fptr)(void *ustruct, double *x));

Parameters

Parameter	Type	Description	Input/Output
handle	KmlSolverTask **	Solver handle, which is a variable passed from a previous step.	Input/Output
ustruct	void *	Pointer to user data. This parameter is transferred as the first parameter each time the preconditioner is called.	Input
(*fptr)	int	User-defined function pointer to the callback function. The callback function performs calculation between the preconditioner and its second parameter.	Input

Return Value

Return Value	Type	Description
KMLSS_NO_ERROR	int	The execution is successful.
KMLSS_NULL_ARGUMENT	int	A null parameter exists in {handle, fptr}.

Dependencies

#include "kml_iss.h"

Examples

C interface:

class pc
{
    public:
        int n;
        double *b;
};
int mut(void *unstruct,double *x)
{
        /*
        Compute the product of the precondition matrix and the vector x,
    the precondition matrix is a diagonal matrix
    */
        int n;
        pc *a;
        a = (pc *)unstruct;
        n = a->n;
        for(int i=0; i<n; i++){
            x[i] = x[i] * a->b[i];
        }
        return 0;
    }

KmlSolverTask *handle;
int ierr;
int n = 8;  

double a[26] = {1.0, 1.0, 2.0, 9.0, 2.0, 1.0, -3.0, 2.0, 3.0, 2.0, 1.0, 1.0, 9.0, -5.0, 2.0, 6.0, 1.0, -3.0, 1.0, 4.0, 1.0, -5.0, 7.0, 2.0,1.0, 2.0};
int ja[26] = {0, 3, 4, 1, 2, 3, 5, 1, 2, 7, 0, 1, 3, 6, 0, 4, 5, 1, 4, 5, 7, 3, 6, 2, 5, 7};
int ia[9] = {0, 3, 7, 10, 14, 17, 21, 23, 26};

pc *unstruct = new pc;
unstruct->b = new double [n];
for(int i=0; i<n; i++){
        unstruct->b[i] = 2;
}
ierr = KmlIssCgInitDI(&handle, n, a, ja, ia);
ierr = KmlIssCgSetUserPreconditionerDI(&handle, unstruct, mut);
if (ierr != 0) {
    printf("\nERROR in KmlIssCgSetUserPreconditionerDI: %d", ierr);
    return 1;
    }

Parent topic: CG