Use literal arrays for FastMath pre-computed tables.

JIRA: MATH-650

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1244725 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math3/util/FastMath.java

@@ -102,8 +102,6 @@ public class FastMath {
      * </p>
      */
     private static /* final */ boolean RECOMPUTE_TABLES_AT_RUNTIME = false;
-    /** Indicator for loading big tables from "resource" files. */
-    private static /* final */ boolean LOAD_RESOURCES = false;
 
     /** log(2) (high bits). */
     private static final double LN_2_A = 0.693147063255310059;
@@ -3738,10 +3736,6 @@ public class FastMath {
                         EXP_INT_TABLE_B[FastMath.EXP_INT_TABLE_MAX_INDEX - i] = recip[1];
                     }
                 }
-            } else if (LOAD_RESOURCES) {
-                final double[][] expInt = FastMathResources.loadExpInt();
-                EXP_INT_TABLE_A = expInt[0];
-                EXP_INT_TABLE_B = expInt[1];
             } else {
                 EXP_INT_TABLE_A = FastMathLiteralArrays.loadExpIntA();
                 EXP_INT_TABLE_B = FastMathLiteralArrays.loadExpIntB();
@@ -3775,10 +3769,6 @@ public class FastMath {
                     EXP_FRAC_TABLE_A[i] = tmp[0];
                     EXP_FRAC_TABLE_B[i] = tmp[1];
                 }
-            } else if (LOAD_RESOURCES) {
-                final double[][] expFrac = FastMathResources.loadExpFrac();
-                EXP_FRAC_TABLE_A = expFrac[0];
-                EXP_FRAC_TABLE_B = expFrac[1];
             } else {
                 EXP_FRAC_TABLE_A = FastMathLiteralArrays.loadExpFracA();
                 EXP_FRAC_TABLE_B = FastMathLiteralArrays.loadExpFracB();
@@ -3800,8 +3790,6 @@ public class FastMath {
                     final double d = Double.longBitsToDouble( (((long) i) << 42) | 0x3ff0000000000000L );
                     LN_MANT[i] = FastMathCalc.slowLog(d);
                 }
-            } else if (LOAD_RESOURCES) {
-                LN_MANT = FastMathResources.loadLnMant();
             } else {
                 LN_MANT = FastMathLiteralArrays.loadLnMant();
             }

src/main/java/org/apache/commons/math3/util/FastMathResources.java

@@ -1,298 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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 org.apache.commons.math3.util;
-
-import java.io.File;
-import java.io.DataOutputStream;
-import java.io.InputStream;
-import java.io.DataInputStream;
-import java.io.BufferedOutputStream;
-import java.io.BufferedInputStream;
-import java.io.FileOutputStream;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.nio.ByteBuffer;
-import java.nio.DoubleBuffer;
-import org.apache.commons.math3.exception.MathInternalError;
-
-/**
- * Utility class for saving and loading tabulated data used by
- * {@link FastMath}.
- *
- * @version $Id$
- */
-class FastMathResources {
-    /**
-     * Resource directory. Assuming that this class and the resource files
-     * are located in the same package as "FastMath".
-     */
-    private static final String RES_DIR = "data/" +
-        FastMath.class.getPackage().getName().replace('.', '/') + "/";
-    /** File resource prefix. */
-    private static final String RES_PREFIX = RES_DIR + "FastMath__";
-    /** Resource basename for "EXP_INT_TABLE_A" and "EXP_INT_TABLE_B". */
-    private static final String EXP_INT = "exp_int";
-    /** Resource basename for "EXP_FRAC_TABLE_A" and "EXP_FRAC_TABLE_B". */
-    private static final String EXP_FRAC = "exp_frac";
-    /** Resource basename for "LN_MANT". */
-    private static final String LN_MANT = "ln_mant";
-    /** Number of bytes in a "double". */
-    private static final int BYTES_IN_DOUBLE = Double.SIZE / Byte.SIZE;
-
-    /**
-     * Class contains only static methods.
-     */
-    private FastMathResources() {}
-
-    /**
-     * Compute and save all the resources.
-     */
-    static void createAll() {
-        // Create resource directory.
-        final File resDir = new File(RES_DIR);
-        if (resDir.exists()) {
-            if (!resDir.isDirectory()) {
-                throw new MathInternalError();
-            }
-        } else {
-            try {
-                resDir.mkdirs();
-            } catch (SecurityException e) {
-                throw new MathInternalError(e);
-            }
-        }
-
-        // "EXP_INT" tables.
-        final double[] expIntA = new double[FastMath.EXP_INT_TABLE_LEN];
-        final double[] expIntB = new double[FastMath.EXP_INT_TABLE_LEN];
-
-        final double tmp[] = new double[2];
-        final double recip[] = new double[2];
-
-        for (int i = 0; i < FastMath.EXP_INT_TABLE_MAX_INDEX; i++) {
-            FastMathCalc.expint(i, tmp);
-            expIntA[i + FastMath.EXP_INT_TABLE_MAX_INDEX] = tmp[0];
-            expIntB[i + FastMath.EXP_INT_TABLE_MAX_INDEX] = tmp[1];
-
-            if (i != 0) {
-                // Negative integer powers.
-                FastMathCalc.splitReciprocal(tmp, recip);
-                expIntA[FastMath.EXP_INT_TABLE_MAX_INDEX - i] = recip[0];
-                expIntB[FastMath.EXP_INT_TABLE_MAX_INDEX - i] = recip[1];
-            }
-        }
-
-        saveTable2d(EXP_INT, new double[][] { expIntA, expIntB });
-
-        // "EXP_FRAC" tables.
-        final double[] expFracA = new double[FastMath.EXP_FRAC_TABLE_LEN];
-        final double[] expFracB = new double[FastMath.EXP_FRAC_TABLE_LEN];
-
-        for (int i = 0; i < FastMath.EXP_FRAC_TABLE_LEN; i++) {
-            FastMathCalc.slowexp(i / 1024d, tmp); // TWO_POWER_10
-            expFracA[i] = tmp[0];
-            expFracB[i] = tmp[1];
-        }
-
-        saveTable2d(EXP_FRAC, new double[][] { expFracA, expFracB });
-
-        // "LN_MANT" table.
-        final double[][] lnMant = new double[FastMath.LN_MANT_LEN][];
-
-        for (int i = 0; i < FastMath.LN_MANT_LEN; i++) {
-            final double d = Double.longBitsToDouble((((long) i) << 42) |
-                                                     0x3ff0000000000000L);
-            lnMant[i] = FastMathCalc.slowLog(d);
-        }
-
-        saveTable2d(LN_MANT, transpose(lnMant));
-    }
-
-    /**
-     * Load "EXP_INT" tables.
-     * "EXP_INT_TABLE_A" is at index 0.
-     * "EXP_INT_TABLE_B" is at index 1.
-     *
-     * @return the retrieved data.
-     */
-    static double[][] loadExpInt() {
-        return loadTable2d(EXP_INT, 2, FastMath.EXP_INT_TABLE_LEN);
-    }
-
-    /**
-     * Load "EXP_FRAC" tables.
-     * "EXP_FRAC_TABLE_A" is at index 0.
-     * "EXP_FRAC_TABLE_B" is at index 1.
-     *
-     * @return the retrieved data.
-     */
-    static double[][] loadExpFrac() {
-        return loadTable2d(EXP_FRAC, 2, FastMath.EXP_FRAC_TABLE_LEN);
-    }
-
-    /**
-     * Load "LN_MANT".
-     *
-     * @return the retrieved data.
-     */
-    static double[][] loadLnMant() {
-        return transpose(loadTable2d(LN_MANT, 2, FastMath.LN_MANT_LEN));
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @return an output stream.
-     * @throws FileNotFoundException if the file cannot be opened.
-     */
-    private static DataOutputStream out(String name)
-        throws FileNotFoundException {
-        final String fullName = RES_PREFIX + name;
-        return new DataOutputStream(new BufferedOutputStream(new FileOutputStream(fullName)));
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @param data Data to be stored.
-     */
-    private static void saveTable1d(String name,
-                                    double[] data) {
-        final int len = data.length;
-
-        try {
-            final DataOutputStream out = out(name);
-
-            for (int i = 0; i < len; i++) {
-                out.writeDouble(data[i]);
-            }
-
-            out.close();
-        } catch (IOException e) {
-            throw new MathInternalError(e);
-        }
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @param data Data to be stored.
-     */
-    private static void saveTable2d(String name,
-                                    double[][] data) {
-        final int len = data.length;
-        final int rowLen = data[0].length;
-
-        try {
-            final DataOutputStream out = out(name);
-
-            for (int i = 0; i < len; i++) {
-                for (int j = 0; j < rowLen; j++) {
-                    out.writeDouble(data[i][j]);
-                }
-            }
-
-            out.close();
-        } catch (IOException e) {
-            throw new MathInternalError(e);
-        }
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @return an input stream.
-     * @throws FileNotFoundException if the resource cannot be accessed.
-     */
-    private static DataInputStream in(String name)
-        throws FileNotFoundException {
-        final String fullName = "/" + RES_PREFIX + name;
-        final InputStream in = FastMathResources.class.getResourceAsStream(fullName);
-        return new DataInputStream(new BufferedInputStream(in));
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @param len Size of the data.
-     * @return the retrieved data.
-     */
-    private static double[] loadTable1d(String name,
-                                        int len) {
-        try {
-            final DataInputStream in = in(name);
-
-            final double[] data = new double[len];
-            for (int i = 0; i < len; i++) {
-                data[i] = in.readDouble();
-            }
-
-            in.close();
-            return data;
-        } catch (IOException e) {
-            throw new MathInternalError(e);
-        }
-    }
-
-    /**
-     * @param name Basename of the resource.
-     * @param len Size of the table.
-     * @param rowLen Size of each row of the table.
-     * @return the retrieved data.
-     */
-    private static double[][] loadTable2d(String name,
-                                          int len,
-                                          int rowLen) {
-        try {
-            final DataInputStream in = in(name);
-            final byte[] b = new byte[BYTES_IN_DOUBLE * rowLen];
-            final double[][] data = new double[len][rowLen];
-            final ByteBuffer bBuf = ByteBuffer.wrap(b);
-
-            for (int i = 0; i < len; i++) {
-                in.readFully(b);
-                final DoubleBuffer dBuf = bBuf.asDoubleBuffer();
-                for (int j = 0; j < rowLen; j++) {
-                    data[i][j] = dBuf.get();
-                }
-            }
-
-            in.close();
-            return data;
-        } catch (IOException e) {
-            throw new MathInternalError(e);
-        }
-    }
-
-    /**
-     * Transposes a two-dimensional array: The number of rows becomes the
-     * number of columns and vice-versa.
-     * The array must be rectangular (same number of colums in each row).
-     *
-     * @param data Array to be transposed.
-     * @return the transposed array.
-     */
-    private static double[][] transpose(double[][] data) {
-        final int rowLen = data.length;
-        final int len = data[0].length;
-        final double[][] tData = new double[len][rowLen];
-
-        for (int i = 0; i < len; i++) {
-            for (int j = 0; j < rowLen; j++) {
-                tData[i][j] = data[j][i];
-            }
-        }
-
-        return tData;
-    }
-}

src/site/xdoc/changes.xml

@@ -52,9 +52,12 @@ The <action> type attribute can be add,update,fix,remove.
     If the output is not quite correct, check for invisible trailing spaces!
      -->
     <release version="3.0" date="TBD" description="TBD">
+      <action dev="sebb" type="fix" issue="MATH-650" >
+        Added pre-computed arrays to speed up initial loading time for FastMath.
+      </action>
       <action dev="luc" type="update">
         Resources for error messages translations have been moved out of META-INF
-        folder in the jar, to avoid interferences with some build systems
+        folder in the jar, to avoid interferences with some build systems.
       </action>
       <action dev="erans" type="fix" issue="MATH-744" due-to="Thundre">
         Fixed "doubleValue" and "floatValue" method in "BigFraction" when

src/test/java/org/apache/commons/math3/util/FastMathLoadCheck.java

@@ -1,120 +0,0 @@
-package org.apache.commons.math3.util;
-
-import java.lang.reflect.Field;
-
-/*
- * FastMath load performance test - requires that
- * <ul>
- *  <li>{@code FastMath.RECOMPUTE_TABLES_AT_RUNTIME}</li>
- *  <li>{@code FastMath.LOAD_RESOURCES}</li>
- * </ul>
- * be non-"final".
- * 
- * For example, this shell command:
- * <pre>
- *  $ for max in false true ; do for how in compute resources array; do java -cp target/classes:target/test-classes org.apache.commons.math3.util.FastMathLoadCheck $max $how 4 ; done ; done
- * </pre>
- * will produce an output similar to the following:
- * <pre>
- * Using exp(100); how=computeUsing exp(100); how=compute
- *     times       result
- *  43534147 2.688117e+43
- *      4547 2.688117e+43
- *      1970 2.688117e+43
- *      1823 2.688117e+43
- *
- * Using exp(100); how=array
- *     times       result
- *  12596573 2.688117e+43
- *      4484 2.688117e+43
- *      1861 2.688117e+43
- *      1864 2.688117e+43
- *
- * Using exp(100); how=resources
- *     times       result
- *  13087186 2.688117e+43
- *      4974 2.688117e+43
- *      1834 2.688117e+43
- *      1900 2.688117e+43
- *
- * Using max(0,0); how=compute
- *     times       result
- *      3172 0.000000e+00
- *       692 0.000000e+00
- *       385 0.000000e+00
- *       358 0.000000e+00
- *
- * Using max(0,0); how=array
- *     times       result
- *      2746 0.000000e+00
- *       527 0.000000e+00
- *       382 0.000000e+00
- *       390 0.000000e+00
- *
- * Using max(0,0); how=resources
- *     times       result
- *      3762 0.000000e+00
- *       506 0.000000e+00
- *       394 0.000000e+00
- *       364 0.000000e+00
- * </pre>
- */
-public class FastMathLoadCheck {
-    private final static String COMP = "compute";
-    private final static String RES = "resources";
-    private final static String ARR = "array";
-
-    private static int LOOPS = 10;
-    private static boolean MAX = false;
-    private static String how = ARR;
-
-    public static void main(String[] args) throws Exception {
-        if (args.length > 0) MAX = Boolean.valueOf(args[0]);
-        if (args.length > 1) how = args[1];
-        if (args.length > 2) LOOPS = Integer.valueOf(args[2]);
-        p("Using "+ (MAX ? "max(0,0)" : "exp(100)") + "; how=" + how + "\n");
-
-        final Field recompute = FastMath.class.getDeclaredField("RECOMPUTE_TABLES_AT_RUNTIME");
-        final Field load = FastMath.class.getDeclaredField("LOAD_RESOURCES");
-        recompute.setAccessible(true);
-        load.setAccessible(true);
-        if (how.equals(COMP)) {
-            recompute.setBoolean(null, true);
-            load.setBoolean(null, false);
-        } else if (how.equals(RES)) {
-            recompute.setBoolean(null, false);
-            load.setBoolean(null, true);
-        } else if (how.equals(ARR)) {
-            recompute.setBoolean(null, false);
-            load.setBoolean(null, false);
-        } else {
-            throw new IllegalArgumentException("'how' must be 'compute' or 'resources' or 'array'");
-        }
-        recompute.setAccessible(false);
-        load.setAccessible(false);
-
-        test();
-    }
-    private static void test(){
-        p("%9s %12s\n", "times", "result");
-        double result;
-        for(int i = 0; i < LOOPS; i++) {
-            long t1 = System.nanoTime();
-            if (MAX) {
-                result = FastMath.max(0, 0);
-            } else {
-                result = FastMath.exp(100);
-            }
-            long t2 = System.nanoTime();
-            p("%9d %e\n", t2 - t1, result);
-        }
-        p("\n");
-    }
-
-    private static void p(String format, Object ... p){
-        System.out.printf(format, p);
-    }
-    private static void p(Object p){
-        System.out.print(p);
-    }
-}

src/test/java/org/apache/commons/math3/util/FastMathResourcesSave.java

@@ -1,32 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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 org.apache.commons.math3.util;
-
-/**
- * Not a test class.
- * It is used to generate the resource data used by the "FastMath" class.
- * You should run it from inside the "resources" directory, i.e. use as:
- * <pre>
- *  $ cd src/main/resources/
- *  $ java -cp ../../../target/classes:../../../target/test-classes org.apache.commons.math3.util.FastMathResourcesSave
- * </pre>
- */
-public class FastMathResourcesSave {
-    public static void main(String[] args) throws Exception {
-        FastMathResources.createAll();
-    }
-}