/*
* Copyright 2000-2016 JetBrains s.r.o.
*
* 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 com.intellij.util;
/**
* @author Sergey.Malenkov
* @see Vector
*/
public final class Matrix {
public static Matrix create(int height, double... values) {
if (values.length == 0) throw new IllegalArgumentException("no values");
if (height <= 0) throw new IllegalArgumentException("unexpected height");
int width = values.length / height;
if (width * height != values.length) throw new IllegalArgumentException("unexpected amount of values");
return new Matrix(width, height, values.clone());
}
public static Matrix createIdentity(int size) {
if (size <= 0) throw new IllegalArgumentException("unexpected size");
double[] array = new double[size * size];
for (int index = 0, i = 0; i < size; i++, index += size + 1) array[index] = 1;
return new Matrix(size, size, array);
}
public static Matrix createColumn(Vector vector) {
return new Matrix(1, vector.getSize(), vector);
}
public static Matrix createRow(Vector vector) {
return new Matrix(vector.getSize(), 1, vector);
}
@Override
public boolean equals(Object object) {
if (object instanceof Matrix) {
Matrix matrix = (Matrix)object;
return width == matrix.width && height == matrix.height && vector.equals(matrix.vector);
}
return false;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Matrix ").append(height).append("x").append(width).append(" { ");
for (int i = 0, h = 0; h < height; h++) {
if (h != 0) sb.append(", ");
sb.append("{");
for (int w = 0; w < width; w++, i++) {
if (w != 0) sb.append(", ");
sb.append(vector.get(i));
}
sb.append("}");
}
return sb.append(" }").toString();
}
public double get(int column, int row) {
validate(column, width);
validate(row, height);
return vector.get(column + row * width);
}
public int getColumns() {
return width;
}
public Vector getColumn(final int column) {
validate(column, width);
return new Vector.Modified(vector) {
@Override
public double get(int row) {
validate(row, height);
return super.get(column + row * width);
}
@Override
public int getSize() {
return height;
}
};
}
public int getRows() {
return height;
}
public Vector getRow(final int row) {
validate(row, height);
return new Vector.Modified(vector) {
@Override
public double get(int column) {
validate(column, width);
return super.get(column + row * width);
}
@Override
public int getSize() {
return width;
}
};
}
public Matrix plus(Matrix matrix) {
if (getColumns() != matrix.getColumns()) throw new IllegalArgumentException("columns mismatch");
if (getRows() != matrix.getRows()) throw new IllegalArgumentException("rows mismatch");
return new Matrix(width, height, vector.plus(matrix.vector));
}
public Matrix minus(Matrix matrix) {
if (getColumns() != matrix.getColumns()) throw new IllegalArgumentException("columns mismatch");
if (getRows() != matrix.getRows()) throw new IllegalArgumentException("rows mismatch");
return new Matrix(width, height, vector.minus(matrix.vector));
}
public Matrix multiply(double value) {
return new Matrix(width, height, vector.multiply(value));
}
public Matrix multiply(Matrix matrix) {
if (getColumns() != matrix.getRows()) throw new IllegalArgumentException("columns mismatch rows");
int width = matrix.getColumns();
int height = getRows();
double[] result = new double[width * height];
for (int i = 0, h = 0; h < height; h++) {
Vector row = getRow(h);
for (int w = 0; w < width; w++, i++) {
result[i] = row.multiply(matrix.getColumn(w));
}
}
return new Matrix(width, height, result);
}
public Vector multiply(Vector vector) {
if (getColumns() != vector.getSize()) throw new IllegalArgumentException("columns mismatch length");
double[] result = new double[getRows()];
for (int i = 0; i < result.length; i++) result[i] = getRow(i).multiply(vector);
return new Vector(result);
}
public double determinant() {
if (width != height) throw new IllegalArgumentException("not a square");
if (width == 1) return vector.get(0);
if (width == 2) return vector.get(0) * vector.get(3) - vector.get(1) * vector.get(2);
double result = 0;
for (int i = 0; i < width; i++) {
double value = vector.get(i) * exclude(i, 0).determinant();
result -= isEven(i) ? -value : value;
}
return result;
}
public Matrix transpose() {
double[] result = new double[vector.getSize()];
for (int i = 0, w = 0; w < width; w++) {
for (int h = 0; h < height; h++, i++) {
result[i] = get(w, h);
}
}
//noinspection SuspiciousNameCombination
return new Matrix(height, width, result);
}
public Matrix inverse() {
double value = determinant();
if (value == 0) throw new IllegalArgumentException("determinant is 0");
return cofactor().transpose().multiply(1 / value);
}
private Matrix exclude(int column, int row) {
validate(column, width);
validate(row, height);
int width = getColumns() - 1;
if (width == 0) throw new IllegalArgumentException("cannot exclude last column");
int height = getRows() - 1;
if (height == 0) throw new IllegalArgumentException("cannot exclude last row");
double[] result = new double[width * height];
int index = 0;
for (int i = 0, h = 0; h <= height; h++) {
for (int w = 0; w <= width; w++, i++) {
if (w != column && h != row) {
result[index++] = vector.get(i);
}
}
}
return new Matrix(width, height, result);
}
private Matrix cofactor() {
if (width != height) throw new IllegalArgumentException("not a square");
double[] result = new double[vector.getSize()];
for (int i = 0, h = 0; h < height; h++) {
for (int w = 0; w < width; w++, i++) {
double value = exclude(w, h).determinant();
result[i] = isEven(w) != isEven(h) ? -value : value;
}
}
return new Matrix(width, height, result);
}
private final int width;
private final int height;
private final Vector vector;
private Matrix(int width, int height, double... values) {
this(width, height, new Vector(values));
}
private Matrix(int width, int height, Vector vector) {
this.width = width;
this.height = height;
this.vector = vector;
}
private static boolean isEven(int i) {
return i % 2 == 0;
}
private static void validate(int index, int max) {
if (index < 0 || max <= index) throw new ArrayIndexOutOfBoundsException(index);
}
}