From 695dc3bdcc17abe96236116bb8481cd6cc21db4a Mon Sep 17 00:00:00 2001
From: Gilles Sadowski <erans@apache.org>
Date: Tue, 17 May 2011 21:38:45 +0000
Subject: [PATCH] MATH-574 Allow outer product of vectors of different sizes.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1104575 13f79535-47bb-0310-9956-ffa450edef68
---
 .../math/linear/SparseFieldVector.java        | 10 ++++-----
 .../math/linear/SparseFieldVectorTest.java    | 22 +++++++++++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/apache/commons/math/linear/SparseFieldVector.java b/src/main/java/org/apache/commons/math/linear/SparseFieldVector.java
index b9f0d2204..13f32a230 100644
--- a/src/main/java/org/apache/commons/math/linear/SparseFieldVector.java
+++ b/src/main/java/org/apache/commons/math/linear/SparseFieldVector.java
@@ -409,8 +409,8 @@ public class SparseFieldVector<T extends FieldElement<T>> implements FieldVector
      * if the dimensions do not match.
      */
     public FieldMatrix<T> outerProduct(SparseFieldVector<T> v) {
-        checkVectorDimensions(v.getDimension());
-        SparseFieldMatrix<T> res = new SparseFieldMatrix<T>(field, virtualSize, virtualSize);
+        final int n = v.getDimension();
+        SparseFieldMatrix<T> res = new SparseFieldMatrix<T>(field, virtualSize, n);
         OpenIntToFieldHashMap<T>.Iterator iter = entries.iterator();
         while (iter.hasNext()) {
             iter.advance();
@@ -425,14 +425,14 @@ public class SparseFieldVector<T extends FieldElement<T>> implements FieldVector
 
     /** {@inheritDoc} */
     public FieldMatrix<T> outerProduct(T[] v) {
-        checkVectorDimensions(v.length);
-        FieldMatrix<T> res = new SparseFieldMatrix<T>(field, virtualSize, virtualSize);
+        final int n = v.length;
+        FieldMatrix<T> res = new SparseFieldMatrix<T>(field, virtualSize, n);
         OpenIntToFieldHashMap<T>.Iterator iter = entries.iterator();
         while (iter.hasNext()) {
             iter.advance();
             int row = iter.key();
             FieldElement<T>value = iter.value();
-            for (int col = 0; col < virtualSize; col++) {
+            for (int col = 0; col < n; col++) {
                 res.setEntry(row, col, value.multiply(v[col]));
             }
         }
diff --git a/src/test/java/org/apache/commons/math/linear/SparseFieldVectorTest.java b/src/test/java/org/apache/commons/math/linear/SparseFieldVectorTest.java
index b1976a063..50edb309d 100644
--- a/src/test/java/org/apache/commons/math/linear/SparseFieldVectorTest.java
+++ b/src/test/java/org/apache/commons/math/linear/SparseFieldVectorTest.java
@@ -170,6 +170,28 @@ public class SparseFieldVectorTest {
 
     }
 
+    @Test
+    public void testOuterProduct() {
+        final SparseFieldVector<Fraction> u
+            = new SparseFieldVector<Fraction>(FractionField.getInstance(),
+                                              new Fraction[] {new Fraction(1),
+                                                              new Fraction(2),
+                                                              new Fraction(-3)});
+        final SparseFieldVector<Fraction> v
+            = new SparseFieldVector<Fraction>(FractionField.getInstance(),
+                                              new Fraction[] {new Fraction(4),
+                                                              new Fraction(-2)});
+
+        final FieldMatrix<Fraction> uv = u.outerProduct(v);
+
+        final double tol = Math.ulp(1d);
+        Assert.assertEquals(new Fraction(4).doubleValue(), uv.getEntry(0, 0).doubleValue(), tol);
+        Assert.assertEquals(new Fraction(-2).doubleValue(), uv.getEntry(0, 1).doubleValue(), tol);
+        Assert.assertEquals(new Fraction(8).doubleValue(), uv.getEntry(1, 0).doubleValue(), tol);
+        Assert.assertEquals(new Fraction(-4).doubleValue(), uv.getEntry(1, 1).doubleValue(), tol);
+        Assert.assertEquals(new Fraction(-12).doubleValue(), uv.getEntry(2, 0).doubleValue(), tol);
+        Assert.assertEquals(new Fraction(6).doubleValue(), uv.getEntry(2, 1).doubleValue(), tol);
+    }
 
     @Test
     public void testMisc() {