package edu.emory.mathcs.csparsej.tdouble;
import edu.emory.mathcs.csparsej.tdouble.Dcs_common.Dcs;
import edu.emory.mathcs.csparsej.tdouble.Dcs_common.Dcsn;
import edu.emory.mathcs.csparsej.tdouble.Dcs_common.Dcss;
/**
* Solves Ax=b where A is symmetric positive definite.
*
* @author Piotr Wendykier (piotr.wendykier@gmail.com)
*
*/
public class Dcs_cholsol {
/**
* Solves Ax=b where A is symmetric positive definite; b is overwritten with
* solution.
*
* @param order
* ordering method to use (0 or 1)
* @param A
* column-compressed matrix, symmetric positive definite, only
* upper triangular part is used
* @param b
* right hand side, b is overwritten with solution
* @return true if successful, false on error
*/
public static boolean cs_cholsol(int order, Dcs A, double[] b) {
double x[];
Dcss S;
Dcsn N;
int n;
boolean ok;
if (!Dcs_util.CS_CSC(A) || b == null)
return (false); /* check inputs */
n = A.n;
S = Dcs_schol.cs_schol(order, A); /* ordering and symbolic analysis */
N = Dcs_chol.cs_chol(A, S); /* numeric Cholesky factorization */
x = new double[n]; /* get workspace */
ok = (S != null && N != null);
if (ok) {
Dcs_ipvec.cs_ipvec(S.pinv, b, x, n); /* x = P*b */
Dcs_lsolve.cs_lsolve(N.L, x); /* x = L\x */
Dcs_ltsolve.cs_ltsolve(N.L, x); /* x = L'\x */
Dcs_pvec.cs_pvec(S.pinv, x, b, n); /* b = P'*x */
}
return (ok);
}
}