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Diffstat (limited to 'java/src/com/android/inputmethod/keyboard/internal/MatrixUtils.java')
| -rw-r--r-- | java/src/com/android/inputmethod/keyboard/internal/MatrixUtils.java | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/java/src/com/android/inputmethod/keyboard/internal/MatrixUtils.java b/java/src/com/android/inputmethod/keyboard/internal/MatrixUtils.java new file mode 100644 index 000000000..4916a15b5 --- /dev/null +++ b/java/src/com/android/inputmethod/keyboard/internal/MatrixUtils.java @@ -0,0 +1,166 @@ +/* + * 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 String TAG = MatrixOperationFailedException.class.getSimpleName(); + 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, "---------------------*/"); + } +} |