| /* |
| * Copyright (C) 2013 The Android Open Source Project |
| * |
| * 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.android.inputmethod.keyboard.internal; |
| |
| import com.android.inputmethod.annotations.UsedForTesting; |
| |
| import android.util.Log; |
| |
| import java.util.Arrays; |
| |
| /** |
| * Utilities for matrix operations. Don't instantiate objects inside this class to prevent |
| * unexpected performance regressions. |
| */ |
| @UsedForTesting |
| public class MatrixUtils { |
| private static final String TAG = MatrixUtils.class.getSimpleName(); |
| public static class MatrixOperationFailedException extends Exception { |
| private static final long serialVersionUID = 4384485606788583829L; |
| |
| public MatrixOperationFailedException(String msg) { |
| super(msg); |
| Log.d(TAG, msg); |
| } |
| } |
| |
| /** |
| * A utility function to inverse matrix. |
| * Find a pivot and swap the row of squareMatrix0 and squareMatrix1 |
| */ |
| private static void findPivotAndSwapRow(final int row, final float[][] squareMatrix0, |
| final float[][] squareMatrix1, final int size) { |
| int ip = row; |
| float pivot = Math.abs(squareMatrix0[row][row]); |
| for (int i = row + 1; i < size; ++i) { |
| if (pivot < Math.abs(squareMatrix0[i][row])) { |
| ip = i; |
| pivot = Math.abs(squareMatrix0[i][row]); |
| } |
| } |
| if (ip != row) { |
| for (int j = 0; j < size; ++j) { |
| final float temp0 = squareMatrix0[ip][j]; |
| squareMatrix0[ip][j] = squareMatrix0[row][j]; |
| squareMatrix0[row][j] = temp0; |
| final float temp1 = squareMatrix1[ip][j]; |
| squareMatrix1[ip][j] = squareMatrix1[row][j]; |
| squareMatrix1[row][j] = temp1; |
| } |
| } |
| } |
| |
| /** |
| * A utility function to inverse matrix. This function calculates answer for each row by |
| * sweeping method of Gauss Jordan elimination |
| */ |
| private static void sweep(final int row, final float[][] squareMatrix0, |
| final float[][] squareMatrix1, final int size) throws MatrixOperationFailedException { |
| final float pivot = squareMatrix0[row][row]; |
| if (pivot == 0) { |
| throw new MatrixOperationFailedException("Inverse failed. Invalid pivot"); |
| } |
| for (int j = 0; j < size; ++j) { |
| squareMatrix0[row][j] /= pivot; |
| squareMatrix1[row][j] /= pivot; |
| } |
| for (int i = 0; i < size; i++) { |
| final float sweepTargetValue = squareMatrix0[i][row]; |
| if (i != row) { |
| for (int j = row; j < size; ++j) { |
| squareMatrix0[i][j] -= sweepTargetValue * squareMatrix0[row][j]; |
| } |
| for (int j = 0; j < size; ++j) { |
| squareMatrix1[i][j] -= sweepTargetValue * squareMatrix1[row][j]; |
| } |
| } |
| } |
| } |
| |
| /** |
| * A function to inverse matrix. |
| * The inverse matrix of squareMatrix will be output to inverseMatrix. Please notice that |
| * the value of squareMatrix is modified in this function and can't be resuable. |
| */ |
| @UsedForTesting |
| public static void inverse(final float[][] squareMatrix, |
| final float[][] inverseMatrix) throws MatrixOperationFailedException { |
| final int size = squareMatrix.length; |
| if (squareMatrix[0].length != size || inverseMatrix.length != size |
| || inverseMatrix[0].length != size) { |
| throw new MatrixOperationFailedException( |
| "--- invalid length. column should be 2 times larger than row."); |
| } |
| for (int i = 0; i < size; ++i) { |
| Arrays.fill(inverseMatrix[i], 0.0f); |
| inverseMatrix[i][i] = 1.0f; |
| } |
| for (int i = 0; i < size; ++i) { |
| findPivotAndSwapRow(i, squareMatrix, inverseMatrix, size); |
| sweep(i, squareMatrix, inverseMatrix, size); |
| } |
| } |
| |
| /** |
| * A matrix operation to multiply m0 and m1. |
| */ |
| @UsedForTesting |
| public static void multiply(final float[][] m0, final float[][] m1, |
| final float[][] retval) throws MatrixOperationFailedException { |
| if (m0[0].length != m1.length) { |
| throw new MatrixOperationFailedException( |
| "--- invalid length for multiply " + m0[0].length + ", " + m1.length); |
| } |
| final int m0h = m0.length; |
| final int m0w = m0[0].length; |
| final int m1w = m1[0].length; |
| if (retval.length != m0h || retval[0].length != m1w) { |
| throw new MatrixOperationFailedException( |
| "--- invalid length of retval " + retval.length + ", " + retval[0].length); |
| } |
| |
| for (int i = 0; i < m0h; i++) { |
| Arrays.fill(retval[i], 0); |
| for (int j = 0; j < m1w; j++) { |
| for (int k = 0; k < m0w; k++) { |
| retval[i][j] += m0[i][k] * m1[k][j]; |
| } |
| } |
| } |
| } |
| |
| /** |
| * A utility function to dump the specified matrix in a readable way |
| */ |
| @UsedForTesting |
| public static void dump(final String title, final float[][] a) { |
| final int column = a[0].length; |
| final int row = a.length; |
| Log.d(TAG, "Dump matrix: " + title); |
| Log.d(TAG, "/*---------------------"); |
| final StringBuilder sb = new StringBuilder(); |
| for (int i = 0; i < row; ++i) { |
| sb.setLength(0); |
| for (int j = 0; j < column; ++j) { |
| sb.append(String.format("%4f", a[i][j])).append(' '); |
| } |
| Log.d(TAG, sb.toString()); |
| } |
| Log.d(TAG, "---------------------*/"); |
| } |
| } |