Java Matrix Product product(final T[][] args)

Description

product

License

Apache License

Declaration

public static <T> List<List<T>> product(final T[][] args) 

Method Source Code

//package com.java2s;
/*/*from  w  w w  . ja va 2 s  . co m*/
 * #%L
 * dither
 * %%
 * Copyright (C) 2015 Jason Gowan
 * %%
 * 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.
 * #L%
 */

import java.util.ArrayList;

import java.util.List;

public class Main {
    public static <T> List<List<T>> product(final T[][] args) {
        final int[] tmp = new int[args.length];
        for (int i = 0; i < tmp.length; i++) {
            tmp[i] = args[i].length;
        }

        final int[][] solution = product(tmp);
        final List<List<T>> results = new ArrayList<List<T>>(
                solution.length);
        for (int i = 0; i < solution.length; i++) {
            final List<T> inner = new ArrayList<T>(args.length);
            results.add(i, inner);
            for (int j = 0; j < args.length; j++) {
                results.get(i).add(j, args[j][solution[i][j]]);
            }
        }
        return results;
    }

    public static int[][] product(final int[] ranges) {
        int length = 1;
        for (int i = 0; i < ranges.length; i++) {
            length *= ranges[i];
            --ranges[i];
        }

        final int[][] results = new int[length][ranges.length];
        final int[] scratch = new int[ranges.length];

        int k = 0;
        final int max = ranges.length - 1;
        for (int i = max;;) {

            if (i == max) {
                for (int val = 0; val <= ranges[i]; val++) {
                    for (int j = 0; j < scratch.length; j++) {
                        results[k][j] = scratch[j];
                    }
                    k++;
                    scratch[i]++;
                }
                scratch[i] = 0;
                i--;
            } else if (i == 0 && scratch[i] >= ranges[i]) {
                return results;
            } else if (scratch[i] < ranges[i]) {
                scratch[i]++;
                i++;
            } else {
                scratch[i] = -1;
                i--;
            }
        }
    }
}

Related

1. matrixInnerProduct(int M, int N, double m1[][], double m2[][])
2. matrixProduct(double[][] A, double[][] B)
3. matrixProduct(double[][] m, double[][] n)
4. matrixProduct(double[][] x, double[] y)
5. matrixProductVDVT(final double[][] V, final double[] d, final double[][] A, int n)