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From er...@apache.org
Subject [2/2] commons-numbers git commit: NUMBERS-30: "safe norm" ported from "Commons Math".
Date Wed, 24 May 2017 15:43:18 GMT
NUMBERS-30: "safe norm" ported from "Commons Math".


Project: http://git-wip-us.apache.org/repos/asf/commons-numbers/repo
Commit: http://git-wip-us.apache.org/repos/asf/commons-numbers/commit/9f1d9ef6
Tree: http://git-wip-us.apache.org/repos/asf/commons-numbers/tree/9f1d9ef6
Diff: http://git-wip-us.apache.org/repos/asf/commons-numbers/diff/9f1d9ef6

Branch: refs/heads/master
Commit: 9f1d9ef6f79adcbf56d8b71663edbf525a4d5be9
Parents: 7a89652
Author: Gilles Sadowski <gilles@harfang.homelinux.org>
Authored: Wed May 24 17:41:06 2017 +0200
Committer: Gilles Sadowski <gilles@harfang.homelinux.org>
Committed: Wed May 24 17:41:06 2017 +0200

----------------------------------------------------------------------
 commons-numbers-core/LICENSE.txt                | 65 +++++++++++++++
 .../apache/commons/numbers/core/SafeNorm.java   | 86 ++++++++++++++++++++
 .../commons/numbers/core/SafeNormTest.java      | 62 ++++++++++++++
 3 files changed, 213 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/commons-numbers/blob/9f1d9ef6/commons-numbers-core/LICENSE.txt
----------------------------------------------------------------------
diff --git a/commons-numbers-core/LICENSE.txt b/commons-numbers-core/LICENSE.txt
index 261eeb9..67c36eb 100644
--- a/commons-numbers-core/LICENSE.txt
+++ b/commons-numbers-core/LICENSE.txt
@@ -199,3 +199,68 @@
    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.
+
+===============================================================================
+
+Apache "Commons Numbers" derivative works:
+
+The "commons-numbers-core" library includes a number of subcomponents
+whose implementation is derived from original sources written in C or
+Fortran.  License terms of the original sources are reproduced below.
+
+===============================================================================
+Code for "SafeNorm" comes from the MINPACK library.
+
+Original source copyright and license statement:
+
+Minpack Copyright Notice (1999) University of Chicago.  All rights reserved
+
+Redistribution and use in source and binary forms, with or
+without modification, are permitted provided that the
+following conditions are met:
+
+1. Redistributions of source code must retain the above
+copyright notice, this list of conditions and the following
+disclaimer.
+
+2. Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following
+disclaimer in the documentation and/or other materials
+provided with the distribution.
+
+3. The end-user documentation included with the
+redistribution, if any, must include the following
+acknowledgment:
+
+   "This product includes software developed by the
+   University of Chicago, as Operator of Argonne National
+   Laboratory.
+
+Alternately, this acknowledgment may appear in the software
+itself, if and wherever such third-party acknowledgments
+normally appear.
+
+4. WARRANTY DISCLAIMER. THE SOFTWARE IS SUPPLIED "AS IS"
+WITHOUT WARRANTY OF ANY KIND. THE COPYRIGHT HOLDER, THE
+UNITED STATES, THE UNITED STATES DEPARTMENT OF ENERGY, AND
+THEIR EMPLOYEES: (1) DISCLAIM ANY WARRANTIES, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE
+OR NON-INFRINGEMENT, (2) DO NOT ASSUME ANY LEGAL LIABILITY
+OR RESPONSIBILITY FOR THE ACCURACY, COMPLETENESS, OR
+USEFULNESS OF THE SOFTWARE, (3) DO NOT REPRESENT THAT USE OF
+THE SOFTWARE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS, (4)
+DO NOT WARRANT THAT THE SOFTWARE WILL FUNCTION
+UNINTERRUPTED, THAT IT IS ERROR-FREE OR THAT ANY ERRORS WILL
+BE CORRECTED.
+
+5. LIMITATION OF LIABILITY. IN NO EVENT WILL THE COPYRIGHT
+HOLDER, THE UNITED STATES, THE UNITED STATES DEPARTMENT OF
+ENERGY, OR THEIR EMPLOYEES: BE LIABLE FOR ANY INDIRECT,
+INCIDENTAL, CONSEQUENTIAL, SPECIAL OR PUNITIVE DAMAGES OF
+ANY KIND OR NATURE, INCLUDING BUT NOT LIMITED TO LOSS OF
+PROFITS OR LOSS OF DATA, FOR ANY REASON WHATSOEVER, WHETHER
+SUCH LIABILITY IS ASSERTED ON THE BASIS OF CONTRACT, TORT
+(INCLUDING NEGLIGENCE OR STRICT LIABILITY), OR OTHERWISE,
+EVEN IF ANY OF SAID PARTIES HAS BEEN WARNED OF THE
+POSSIBILITY OF SUCH LOSS OR DAMAGES.

http://git-wip-us.apache.org/repos/asf/commons-numbers/blob/9f1d9ef6/commons-numbers-core/src/main/java/org/apache/commons/numbers/core/SafeNorm.java
----------------------------------------------------------------------
diff --git a/commons-numbers-core/src/main/java/org/apache/commons/numbers/core/SafeNorm.java
b/commons-numbers-core/src/main/java/org/apache/commons/numbers/core/SafeNorm.java
new file mode 100644
index 0000000..5d077bc
--- /dev/null
+++ b/commons-numbers-core/src/main/java/org/apache/commons/numbers/core/SafeNorm.java
@@ -0,0 +1,86 @@
+/*
+ * 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.numbers.core;
+
+/**
+ * Computes the Cartesian norm (2-norm), handling both overflow and underflow.
+ * Translation of the <a href="http://www.netlib.org/minpack">minpack</a>
+ * "enorm" subroutine.
+ */
+public class SafeNorm {
+    /** Constant. */
+    private static final double R_DWARF = 3.834e-20;
+    /** Constant. */
+    private static final double R_GIANT = 1.304e+19;
+
+    /**
+     * @param v Cartesian coordinates.
+     * @return the 2-norm of the vector.
+     */
+    public static double value(double[] v) {
+        double s1 = 0;
+        double s2 = 0;
+        double s3 = 0;
+        double x1max = 0;
+        double x3max = 0;
+        double floatn = v.length;
+        double agiant = R_GIANT / floatn;
+        for (int i = 0; i < v.length; i++) {
+            double xabs = Math.abs(v[i]);
+            if (xabs < R_DWARF || xabs > agiant) {
+                if (xabs > R_DWARF) {
+                    if (xabs > x1max) {
+                        double r = x1max / xabs;
+                        s1 = 1 + s1 * r * r;
+                        x1max = xabs;
+                    } else {
+                        double r = xabs / x1max;
+                        s1 += r * r;
+                    }
+                } else {
+                    if (xabs > x3max) {
+                        double r = x3max / xabs;
+                        s3 = 1 + s3 * r * r;
+                        x3max = xabs;
+                    } else {
+                        if (xabs != 0) {
+                            double r = xabs / x3max;
+                            s3 += r * r;
+                        }
+                    }
+                }
+            } else {
+                s2 += xabs * xabs;
+            }
+        }
+        double norm;
+        if (s1 != 0) {
+            norm = x1max * Math.sqrt(s1 + (s2 / x1max) / x1max);
+        } else {
+            if (s2 == 0) {
+                norm = x3max * Math.sqrt(s3);
+            } else {
+                if (s2 >= x3max) {
+                    norm = Math.sqrt(s2 * (1 + (x3max / s2) * (x3max * s3)));
+                } else {
+                    norm = Math.sqrt(x3max * ((s2 / x3max) + (x3max * s3)));
+                }
+            }
+        }
+        return norm;
+    }
+}

http://git-wip-us.apache.org/repos/asf/commons-numbers/blob/9f1d9ef6/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/SafeNormTest.java
----------------------------------------------------------------------
diff --git a/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/SafeNormTest.java
b/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/SafeNormTest.java
new file mode 100644
index 0000000..0c4e9bc
--- /dev/null
+++ b/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/SafeNormTest.java
@@ -0,0 +1,62 @@
+/*
+ * 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.numbers.core;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Test cases for the {@link SafeNorm} class.
+ */
+public class SafeNormTest {
+
+    @Test
+    public void testTiny() {
+        final double s = 1e-320;
+        final double[] v = new double[] { s, s };
+        Assert.assertEquals(Math.sqrt(2) * s, SafeNorm.value(v), 0d);
+    }
+
+    @Test
+    public void testBig() {
+        final double s = 1e300;
+        final double[] v = new double[] { s, s };
+        Assert.assertEquals(Math.sqrt(2) * s, SafeNorm.value(v), 0d);
+    }
+
+    @Test
+    public void testOne3D() {
+        final double s = 1;
+        final double[] v = new double[] { s, s, s };
+        Assert.assertEquals(Math.sqrt(3), SafeNorm.value(v), 0d);
+    }
+
+    @Test
+    public void testUnit3D() {
+        Assert.assertEquals(1, SafeNorm.value(new double[] { 1, 0, 0 }), 0d);
+        Assert.assertEquals(1, SafeNorm.value(new double[] { 0, 1, 0 }), 0d);
+        Assert.assertEquals(1, SafeNorm.value(new double[] { 0, 0, 1 }), 0d);
+    }
+
+    @Test
+    public void testSimple() {
+        final double[] v = new double[] { -0.9, 8.7, -6.5, -4.3, -2.1, 0, 1.2, 3.4, -5.6,
7.8, 9.0 };
+        double n = 0;
+        for (int i = 0; i < v.length; i++) {
+            n += v[i] * v[i];
+        }
+        final double expected = Math.sqrt(n);
+        Assert.assertEquals(expected, SafeNorm.value(v), 0d);
+    }
+}


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