Author: mikl
Date: Mon Mar 21 09:28:34 2011
New Revision: 1083713
URL: http://svn.apache.org/viewvc?rev=1083713&view=rev
Log:
Fixes MATH-435 for FieldMatrix<T>, too.
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractFieldMatrix.java
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/FieldMatrix.java
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/FieldMatrixImplTest.java
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractFieldMatrix.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractFieldMatrix.java?rev=1083713&r1=1083712&r2=1083713&view=diff
==============================================================================
---
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractFieldMatrix.java
(original)
+++
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractFieldMatrix.java
Mon Mar 21 09:28:34 2011
@@ -18,6 +18,7 @@
package org.apache.commons.math.linear;
import java.lang.reflect.Array;
+import java.util.ArrayList;
import java.util.Arrays;
import org.apache.commons.math.Field;
@@ -264,6 +265,65 @@ public abstract class AbstractFieldMatri
public FieldMatrix<T> preMultiply(final FieldMatrix<T> m) {
return m.multiply(this);
}
+
+ /** {@inheritDoc} */
+ @Override
+ public FieldMatrix<T> power(final int p) {
+ if (p < 0) {
+ throw new IllegalArgumentException("p must be >= 0");
+ }
+
+ if (!isSquare()) {
+ throw new NonSquareMatrixException(getRowDimension(),
getColumnDimension());
+ }
+
+ if (p == 0) {
+ return MatrixUtils.createFieldIdentityMatrix(this.getField(),
this.getRowDimension());
+ }
+
+ if (p == 1) {
+ return this.copy();
+ }
+
+ final int power = p - 1;
+
+ /*
+ * Only log_2(p) operations is used by doing as follows:
+ * 5^214 = 5^128 * 5^64 * 5^16 * 5^4 * 5^2
+ *
+ * In general, the same approach is used for A^p.
+ */
+
+ final char[] binaryRepresentation = Integer.toBinaryString(power)
+ .toCharArray();
+ final ArrayList<Integer> nonZeroPositions = new ArrayList<Integer>();
+
+ for (int i = 0; i < binaryRepresentation.length; ++i) {
+ if (binaryRepresentation[i] == '1') {
+ final int pos = binaryRepresentation.length - i - 1;
+ nonZeroPositions.add(pos);
+ }
+ }
+
+ ArrayList<FieldMatrix<T>> results = new ArrayList<FieldMatrix<T>>(
+ binaryRepresentation.length);
+
+ results.add(0, this.copy());
+
+ for (int i = 1; i < binaryRepresentation.length; ++i) {
+ final FieldMatrix<T> s = results.get(i - 1);
+ final FieldMatrix<T> r = s.multiply(s);
+ results.add(i, r);
+ }
+
+ FieldMatrix<T> result = this.copy();
+
+ for (Integer i : nonZeroPositions) {
+ result = result.multiply(results.get(i));
+ }
+
+ return result;
+ }
/** {@inheritDoc} */
public T[][] getData() {
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/FieldMatrix.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/FieldMatrix.java?rev=1083713&r1=1083712&r2=1083713&view=diff
==============================================================================
---
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/FieldMatrix.java
(original)
+++
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/FieldMatrix.java
Mon Mar 21 09:28:34 2011
@@ -116,6 +116,17 @@ public interface FieldMatrix<T extends F
FieldMatrix<T> preMultiply(FieldMatrix<T> m);
/**
+ * Returns the result multiplying this with itself <code>p</code> times.
+ * Depending on the type of the field elements, T,
+ * instability for high powers might occur.
+ * @param p raise this to power p
+ * @return this^p
+ * @throws IllegalArgumentException if p < 0
+ * NonSquareMatrixException if the matrix is not square
+ */
+ FieldMatrix<T> power(final int p);
+
+ /**
* Returns matrix entries as a two-dimensional array.
*
* @return a 2-dimensional array of entries.
Modified:
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/FieldMatrixImplTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/FieldMatrixImplTest.java?rev=1083713&r1=1083712&r2=1083713&view=diff
==============================================================================
---
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/FieldMatrixImplTest.java
(original)
+++
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/FieldMatrixImplTest.java
Mon Mar 21 09:28:34 2011
@@ -199,6 +199,52 @@ public final class FieldMatrixImplTest {
TestUtils.assertEquals(m3.multiply(m4), m5);
}
+ @Test
+ public void testPower() {
+ FieldMatrix<Fraction> m = new
Array2DRowFieldMatrix<Fraction>(testData);
+ FieldMatrix<Fraction> mInv = new
Array2DRowFieldMatrix<Fraction>(testDataInv);
+ FieldMatrix<Fraction> mPlusInv = new
Array2DRowFieldMatrix<Fraction>(testDataPlusInv);
+ FieldMatrix<Fraction> identity = new
Array2DRowFieldMatrix<Fraction>(id);
+
+ TestUtils.assertEquals(m.power(0), identity);
+ TestUtils.assertEquals(mInv.power(0), identity);
+ TestUtils.assertEquals(mPlusInv.power(0), identity);
+
+ TestUtils.assertEquals(m.power(1), m);
+ TestUtils.assertEquals(mInv.power(1), mInv);
+ TestUtils.assertEquals(mPlusInv.power(1), mPlusInv);
+
+ FieldMatrix<Fraction> C1 = m.copy();
+ FieldMatrix<Fraction> C2 = mInv.copy();
+ FieldMatrix<Fraction> C3 = mPlusInv.copy();
+
+ // stop at 5 to avoid overflow
+ for (int i = 2; i <= 5; ++i) {
+ C1 = C1.multiply(m);
+ C2 = C2.multiply(mInv);
+ C3 = C3.multiply(mPlusInv);
+
+ TestUtils.assertEquals(m.power(i), C1);
+ TestUtils.assertEquals(mInv.power(i), C2);
+ TestUtils.assertEquals(mPlusInv.power(i), C3);
+ }
+
+ try {
+ FieldMatrix<Fraction> mNotSquare = new
Array2DRowFieldMatrix<Fraction>(testData2T);
+ mNotSquare.power(2);
+ Assert.fail("Expecting NonSquareMatrixException");
+ } catch (NonSquareMatrixException ex) {
+ // ignored
+ }
+
+ try {
+ m.power(-1);
+ Assert.fail("Expecting IllegalArgumentException");
+ } catch (IllegalArgumentException ex) {
+ // ignored
+ }
+ }
+
/** test trace */
@Test
public void testTrace() {
