org.ejml.dense.row.decompose.TriangularSolver_ZDRM Maven / Gradle / Ivy
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/*
* Copyright (c) 2009-2017, Peter Abeles. All Rights Reserved.
*
* This file is part of Efficient Java Matrix Library (EJML).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.ejml.dense.row.decompose;
/**
*
* This contains algorithms for solving systems of equations where T is a
* non-singular triangular complex matrix:
*
* T*x = b
*
* where x and b are vectors, and T is an n by n matrix. T can either be a lower or upper triangular matrix.
*
*
* These functions are designed for use inside of other algorithms. To use them directly
* is dangerous since no sanity checks are performed.
*
*
* @author Peter Abeles
*/
public class TriangularSolver_ZDRM {
/**
*
* This is a forward substitution solver for non-singular upper triangular matrices.
*
* b = U-1b
*
* where b is a vector, U is an n by n matrix.
*
*
* @param U An n by n non-singular upper triangular matrix. Not modified.
* @param b A vector of length n. Modified.
* @param n The size of the matrices.
*/
public static void solveU( double U[] , double []b , int n )
{
// for( int i =n-1; i>=0; i-- ) {
// double sum = b[i];
// for( int j = i+1; j =0; i-- ) {
double sumReal = b[i*2];
double sumImg = b[i*2+1];
int indexU = i*stride+i*2+2;
for( int j = i+1; j
* Solves for non-singular lower triangular matrices with real valued diagonal elements
* using forward substitution.
*
* b = L-1b
*
* where b is a vector, L is an n by n matrix.
*
*
* @param L An n by n non-singular lower triangular matrix. Not modified.
* @param b A vector of length n. Modified.
* @param n The size of the matrices.
*/
public static void solveL_diagReal(double L[], double[] b, int n)
{
// for( int i = 0; i < n; i++ ) {
// double sum = b[i];
// for( int k=0; k
* This is a forward substitution solver for non-singular lower triangular matrices with
* real valued diagonal elements.
*
* b = (LCT)-1b
*
* where b is a vector, L is an n by n matrix.
*
*
* L is a lower triangular matrix, but it comes up with a solution as if it was
* an upper triangular matrix that was computed by conjugate transposing L.
*
*
* @param L An n by n non-singular lower triangular matrix. Not modified.
* @param b A vector of length n. Modified.
* @param n The size of the matrices.
*/
public static void solveConjTranL_diagReal(double L[], double[] b, int n)
{
// for( int i =n-1; i>=0; i-- ) {
// double sum = b[i];
// for( int k = i+1; k =0; i-- ) {
double realSum = b[i*2];
double imagSum = b[i*2+1];
int indexB = (i+1)*2;
for( int k = i+1; k