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 0000000000000000000000000000000000000000..4916a15b5e5b1a3bfb45b8e622124981f788b90a
--- /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, "---------------------*/");
+ }
+}
diff --git a/java/src/com/android/inputmethod/keyboard/internal/SmoothingUtils.java b/java/src/com/android/inputmethod/keyboard/internal/SmoothingUtils.java
new file mode 100644
index 0000000000000000000000000000000000000000..e5665bcdd6eea4cb1a2a97cf484db0e397d82ec8
--- /dev/null
+++ b/java/src/com/android/inputmethod/keyboard/internal/SmoothingUtils.java
@@ -0,0 +1,102 @@
+/*
+ * 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 com.android.inputmethod.keyboard.internal.MatrixUtils.MatrixOperationFailedException;
+
+import android.util.Log;
+
+import java.util.Arrays;
+
+/**
+ * Utilities to smooth coordinates. Currently, we calculate 3d least squares formula by using
+ * Lagrangian smoothing
+ */
+@UsedForTesting
+public class SmoothingUtils {
+ private static final String TAG = SmoothingUtils.class.getSimpleName();
+ private static final boolean DEBUG = false;
+
+ private SmoothingUtils() {
+ // not allowed to instantiate publicly
+ }
+
+ /**
+ * Find a most likely 3d least squares formula for specified coordinates.
+ * "retval" should be a 1x4 size matrix.
+ */
+ @UsedForTesting
+ public static void get3DParameters(final float[] xs, final float[] ys,
+ final float[][] retval) throws MatrixOperationFailedException {
+ final int COEFF_COUNT = 4; // Coefficient count for 3d smoothing
+ if (retval.length != COEFF_COUNT || retval[0].length != 1) {
+ Log.d(TAG, "--- invalid length of 3d retval " + retval.length + ", "
+ + retval[0].length);
+ return;
+ }
+ final int N = xs.length;
+ // TODO: Never isntantiate the matrix
+ final float[][] m0 = new float[COEFF_COUNT][COEFF_COUNT];
+ final float[][] m0Inv = new float[COEFF_COUNT][COEFF_COUNT];
+ final float[][] m1 = new float[COEFF_COUNT][N];
+ final float[][] m2 = new float[N][1];
+
+ // m0
+ for (int i = 0; i < COEFF_COUNT; ++i) {
+ Arrays.fill(m0[i], 0);
+ for (int j = 0; j < COEFF_COUNT; ++j) {
+ final int pow = i + j;
+ for (int k = 0; k < N; ++k) {
+ m0[i][j] += (float) Math.pow((double) xs[k], pow);
+ }
+ }
+ }
+ // m0Inv
+ MatrixUtils.inverse(m0, m0Inv);
+ if (DEBUG) {
+ MatrixUtils.dump("m0-1", m0Inv);
+ }
+
+ // m1
+ for (int i = 0; i < COEFF_COUNT; ++i) {
+ for (int j = 0; j < N; ++j) {
+ m1[i][j] = (i == 0) ? 1.0f : m1[i - 1][j] * xs[j];
+ }
+ }
+
+ // m2
+ for (int i = 0; i < N; ++i) {
+ m2[i][0] = ys[i];
+ }
+
+ final float[][] m0Invxm1 = new float[COEFF_COUNT][N];
+ if (DEBUG) {
+ MatrixUtils.dump("a0", m0Inv);
+ MatrixUtils.dump("a1", m1);
+ }
+ MatrixUtils.multiply(m0Inv, m1, m0Invxm1);
+ if (DEBUG) {
+ MatrixUtils.dump("a2", m0Invxm1);
+ MatrixUtils.dump("a3", m2);
+ }
+ MatrixUtils.multiply(m0Invxm1, m2, retval);
+ if (DEBUG) {
+ MatrixUtils.dump("result", retval);
+ }
+ }
+}
diff --git a/tests/src/com/android/inputmethod/keyboard/internal/MatrixUtilsTests.java b/tests/src/com/android/inputmethod/keyboard/internal/MatrixUtilsTests.java
new file mode 100644
index 0000000000000000000000000000000000000000..e2a11ab9954be3de1ae54c9778519f2ead17068d
--- /dev/null
+++ b/tests/src/com/android/inputmethod/keyboard/internal/MatrixUtilsTests.java
@@ -0,0 +1,84 @@
+/*
+ * 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.keyboard.internal.MatrixUtils.MatrixOperationFailedException;
+
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+
+@SmallTest
+public class MatrixUtilsTests extends AndroidTestCase {
+ // "run tests" -c com.android.inputmethod.keyboard.internal.MatrixUtilsTests
+ private static final boolean DEBUG = false;
+ private static final float EPSILON = 0.00001f;
+
+ private static void assertEqualsFloat(float f0, float f1) {
+ assertEqualsFloat(f0, f1, EPSILON);
+ }
+
+ /* package */ static void assertEqualsFloat(float f0, float f1, float error) {
+ assertTrue(Math.abs(f0 - f1) < error);
+ }
+
+ public void testMulti() {
+ final float[][] matrixA = {{1, 2}, {3, 4}};
+ final float[][] matrixB = {{5, 6}, {7, 8}};
+ final float[][] retval = new float[2][2];
+ try {
+ MatrixUtils.multiply(matrixA, matrixB, retval);
+ } catch (MatrixOperationFailedException e) {
+ assertTrue(false);
+ }
+ if (DEBUG) {
+ MatrixUtils.dump("multi", retval);
+ }
+ assertEqualsFloat(retval[0][0], 19);
+ assertEqualsFloat(retval[0][1], 22);
+ assertEqualsFloat(retval[1][0], 43);
+ assertEqualsFloat(retval[1][1], 50);
+ }
+
+ public void testInverse() {
+ final int N = 4;
+ final float[][] matrix =
+ {{1, 2, 3, 4}, {4, 0, 5, 6}, {6, 4, 2, 0}, {6, 4, 2, 1}};
+ final float[][] inverse = new float[N][N];
+ final float[][] tempMatrix = new float[N][N];
+ for (int i = 0; i < N; ++i) {
+ for (int j = 0; j < N; ++j) {
+ tempMatrix[i][j] = matrix[i][j];
+ }
+ }
+ final float[][] retval = new float[N][N];
+ try {
+ MatrixUtils.inverse(tempMatrix, inverse);
+ } catch (MatrixOperationFailedException e) {
+ assertTrue(false);
+ }
+ try {
+ MatrixUtils.multiply(matrix, inverse, retval);
+ } catch (MatrixOperationFailedException e) {
+ assertTrue(false);
+ }
+ for (int i = 0; i < N; ++i) {
+ for (int j = 0; j < N; ++j) {
+ assertEqualsFloat(((i == j) ? 1.0f : 0.0f), retval[i][j]);
+ }
+ }
+ }
+}
diff --git a/tests/src/com/android/inputmethod/keyboard/internal/SmoothingUtilsTests.java b/tests/src/com/android/inputmethod/keyboard/internal/SmoothingUtilsTests.java
new file mode 100644
index 0000000000000000000000000000000000000000..293741af20a4849c0d04457637dc2989eada86e8
--- /dev/null
+++ b/tests/src/com/android/inputmethod/keyboard/internal/SmoothingUtilsTests.java
@@ -0,0 +1,45 @@
+/*
+ * 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.keyboard.internal.MatrixUtils.MatrixOperationFailedException;
+
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+
+@SmallTest
+public class SmoothingUtilsTests extends AndroidTestCase {
+ // "run tests" -c com.android.inputmethod.keyboard.internal.SmoothingUtilsTests
+ private static final boolean DEBUG = false;
+
+ public void testGet3DParamaters() {
+ final float[] xs = new float[] {0, 1, 2, 3, 4};
+ final float[] ys = new float[] {1, 4, 15, 40, 85}; // y = x^3 + x^2 + x + 1
+ final float[][] retval = new float[4][1];
+ try {
+ SmoothingUtils.get3DParameters(xs, ys, retval);
+ if (DEBUG) {
+ MatrixUtils.dump("3d", retval);
+ }
+ for (int i = 0; i < 4; ++i) {
+ MatrixUtilsTests.assertEqualsFloat(retval[i][0], 1.0f, 0.001f);
+ }
+ } catch (MatrixOperationFailedException e) {
+ assertTrue(false);
+ }
+ }
+}