Phil,
I think we wanted to maintain the existence of setEntry/getDataRef API of the RealMatrixImpl without having it in the RealMatrix Interface. At least until we come up with a strategy for mutability that made more sense then these methods. This last change removed it from both.
Michael,
We are attempting to make the Implementation immutable so that methods calls such as getColumnMatrix(i) and getSubMatrix(xmin,xmax,ymin,ymax) will be able to return submatrice objects of the existing data without duplicating/copying the internal datastore to do so, this will provide efficient means to access the stored values without performing costly array copies on what may be very large double[][]'s or copying objects which may not be in an []. So basically, what we are trying to avoid is that if I do the following
Matrix a = ... Matrix b = a.getColumnMatrix(x);
that if (a) is mutable, then doing something like a.setEntry(x,y,d) will also cause (b) to change, something we should try to avoid, we are trying to work with these more as mathematical objects and not necessarily as "Collection objects".
If you require such mutability, could you take a moment and show an example of the usage you require it for?
-thanks, Mark Diggory
Michael Heuer wrote:
Sorry to be replying to a cvs commit message, but I think perhaps this is taking this idea of immutability too far -- a matrix data structure isn't very useful if you can't even modify the entries.
Wouldn't the pattern used in the Collections interfaces for modifiers be more reasonable here?
interface RealMatrix { ...
/** * Sets the entry in the specified row and column to the specified * value (optional operation). * * ... * @throws UnsupportedOperationException if the <code>setEntry<code> * operation is not supported by this real matrix */ void setEntry(int row, int column, double value) ...; }
I also wanted to mention that I feel that this interface and its implementation seem too closely intertwined with double arrays, as if clients of the API are going to be moving back and forth between the two data representations regularly.
With the Collections interfaces, if I want a List, I'm going to use one, not go back and forth between Lists and arrays. Similarly, if I want to use a RealMatrix, I'd like to use one, not go back and forth between it and 1D and 2D double arrays.
michael
On 12 Oct 2004 [EMAIL PROTECTED] wrote:
psteitz 2004/10/11 23:19:50
Modified: math/xdocs/userguide linear.xml math/src/java/org/apache/commons/math/linear RealMatrix.java RealMatrixImpl.java math/src/test/org/apache/commons/math/linear RealMatrixImplTest.java Log: Removed data mutators from RealMatrix interface and RealMatrixImpl.
Revision Changes Path 1.9 +4 -5 jakarta-commons/math/xdocs/userguide/linear.xml
Index: linear.xml =================================================================== RCS file: /home/cvs/jakarta-commons/math/xdocs/userguide/linear.xml,v retrieving revision 1.8 retrieving revision 1.9 diff -u -r1.8 -r1.9 --- linear.xml 17 May 2004 05:57:38 -0000 1.8 +++ linear.xml 12 Oct 2004 06:19:50 -0000 1.9 @@ -56,11 +56,10 @@
// One more with three rows, two columns double[][] matrixData2 = { {1d,2d}, {2d,5d}, {1d, 7d}}; -RealMatrix n = new RealMatixImpl(); -n.setData(matrixData2); +RealMatrix n = new RealMatixImpl(matrixData2);
-// Note: both constructor and setData make -// Fresh copies of input double[][] arrays +// Note: constructor makes a +// Fresh copy of the input double[][] array
// Now multiply m by n RealMatrix p = m.multiply(n);
1.25 +1 -27 jakarta-commons/math/src/java/org/apache/commons/math/linear/RealMatrix.java
Index: RealMatrix.java =================================================================== RCS file: /home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/linear/RealMatrix.java,v retrieving revision 1.24 retrieving revision 1.25 diff -u -r1.24 -r1.25 --- RealMatrix.java 9 Oct 2004 22:39:22 -0000 1.24 +++ RealMatrix.java 12 Oct 2004 06:19:50 -0000 1.25 @@ -94,14 +94,6 @@ double[][] getData();
/** - * Overwrites the underlying data for the matrix with - * a fresh copy of <code>data</code>. - * - * @param data 2-dimensional array of entries - */ - void setData(double[][] data); - - /** * Returns the <a href="http://mathworld.wolfram.com/MaximumAbsoluteRowSumNorm.html";> * maximum absolute row sum norm</a> of the matrix. * @@ -197,24 +189,6 @@ * @throws MatrixIndexException if the row or column index is not valid */ double getEntry(int row, int column) throws MatrixIndexException; - - /** - * Sets the entry in the specified row and column to the specified value. - * <p> - * Row and column indices start at 0 and must satisfy - * <ul> - * <li><code>0 <= row < rowDimension</code></li> - * <li><code> 0 <= column < columnDimension</code></li> - * </ul> - * otherwise a <code>MatrixIndexException</code> is thrown. - * - * @param row row location of entry to be set - * @param column column location of entry to be set - * @param value value to set - * @throws MatrixIndexException if the row or column index is not valid - */ - void setEntry(int row, int column, double value) - throws MatrixIndexException;
/** * Returns the transpose of this matrix.
1.33 +8 -57 jakarta-commons/math/src/java/org/apache/commons/math/linear/RealMatrixImpl.java
Index: RealMatrixImpl.java =================================================================== RCS file: /home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/linear/RealMatrixImpl.java,v retrieving revision 1.32 retrieving revision 1.33 diff -u -r1.32 -r1.33 --- RealMatrixImpl.java 10 Oct 2004 18:00:33 -0000 1.32 +++ RealMatrixImpl.java 12 Oct 2004 06:19:50 -0000 1.33 @@ -21,8 +21,8 @@
/** - * Implementation for RealMatrix using a double[][] array to store entries - * and <a href="http://www.math.gatech.edu/~bourbaki/math2601/Web-notes/2num.pdf";> + * Implementation for RealMatrix using a double[][] array to store entries and + * <a href="http://www.math.gatech.edu/~bourbaki/math2601/Web-notes/2num.pdf";> * LU decompostion</a> to support linear system * solution and inverse. * <p> @@ -34,12 +34,11 @@ * <p> * <strong>Usage notes</strong>:<br> * <ul><li> - * The LU decomposition is stored and reused on subsequent calls. If matrix - * data are modified using any of the public setXxx methods, the saved - * decomposition is discarded. If data are modified via references to the - * underlying array obtained using <code>getDataRef()</code>, then the stored - * LU decomposition will not be discarded. In this case, you need to - * explicitly invoke <code>LUDecompose()</code> to recompute the decomposition + * The LU decomposition is cached and reused on subsequent calls. + * If data are modified via references to the underlying array obtained using + * <code>getDataRef()</code>, then the stored LU decomposition will not be + * discarded. In this case, you need to explicitly invoke + * <code>LUDecompose()</code> to recompute the decomposition * before using any of the methods above.</li> * <li> * As specified in the [EMAIL PROTECTED] RealMatrix} interface, matrix element indexing @@ -280,17 +279,6 @@ }
/** - * Overwrites the underlying data for the matrix - * with a fresh copy of <code>inData</code>. - * - * @param inData 2-dimensional array of entries - */ - public void setData(double[][] inData) { - copyIn(inData); - lu = null; - } - - /** * Returns a reference to the underlying data array. * <p> * Does not make a fresh copy of the underlying data. @@ -302,19 +290,6 @@ }
/** - * Overwrites the underlying data for the matrix - * with a reference to <code>inData</code>. - * <p> - * Does not make a fresh copy of <code>data</code>. - * - * @param inData 2-dimensional array of entries - */ - public void setDataRef(double[][] inData) { - this.data = inData; - lu = null; - } - - /** * * @return norm */ @@ -495,30 +470,6 @@ throw new MatrixIndexException("matrix entry does not exist"); } return data[row][column]; - } - - /** - * Sets the entry in the specified row and column to the specified value. - * <p> - * Row and column indices start at 0 and must satisfy - * <ul> - * <li><code>0 <= row < rowDimension</code></li> - * <li><code> 0 <= column < columnDimension</code></li> - * </ul> - * otherwise a <code>MatrixIndexException</code> is thrown. - * - * @param row row location of entry to be set - * @param column column location of entry to be set - * @param value value to set - * @throws MatrixIndexException if the row or column index is not valid - */ - public void setEntry(int row, int column, double value) - throws MatrixIndexException { - if (!isValidCoordinate(row,column)) { - throw new MatrixIndexException("matrix entry does not exist"); - } - data[row][column] = value; - lu = null; }
/**
1.20 +28 -46 jakarta-commons/math/src/test/org/apache/commons/math/linear/RealMatrixImplTest.java
Index: RealMatrixImplTest.java =================================================================== RCS file: /home/cvs/jakarta-commons/math/src/test/org/apache/commons/math/linear/RealMatrixImplTest.java,v retrieving revision 1.19 retrieving revision 1.20 diff -u -r1.19 -r1.20 --- RealMatrixImplTest.java 10 Oct 2004 18:01:16 -0000 1.19 +++ RealMatrixImplTest.java 12 Oct 2004 06:19:50 -0000 1.20 @@ -111,25 +111,13 @@ assertEquals("testData2 row dimension",m2.getRowDimension(),2); assertEquals("testData2 column dimension",m2.getColumnDimension(),3); assertTrue("testData2 is not square",!m2.isSquare()); - RealMatrixImpl m3 = new RealMatrixImpl(); - m3.setData(testData); }
/** test copy functions */ public void testCopyFunctions() { RealMatrixImpl m = new RealMatrixImpl(testData); - RealMatrixImpl m2 = new RealMatrixImpl(testData2); - m2.setData(m.getData()); - assertClose("getData",m2,m,entryTolerance); - // no dangling reference... - m2.setEntry(1,1,2000d); - RealMatrixImpl m3 = new RealMatrixImpl(testData); - assertClose("no getData side effect",m,m3,entryTolerance); - m3 = (RealMatrixImpl) m.copy(); - double[][] stompMe = {{1d,2d,3d}}; - m3.setDataRef(stompMe); - assertClose("no copy side effect",m,new RealMatrixImpl(testData), - entryTolerance); + RealMatrixImpl m2 = new RealMatrixImpl(m.getData()); + assertEquals(m2,m); }
/** test add */ @@ -418,22 +406,14 @@ } }
- public void testEntryMutators() { + public void testGetEntry() { RealMatrix m = new RealMatrixImpl(testData); assertEquals("get entry",m.getEntry(0,1),2d,entryTolerance); - m.setEntry(1,2,100d); - assertEquals("get entry",m.getEntry(1,2),100d,entryTolerance); - try { - double x = m.getEntry(-1,2); - fail("expecting MatrixIndexException"); - } catch (MatrixIndexException ex) { - ; - } try { - m.setEntry(1,4,200d); - fail("expecting MatrixIndexException"); + m.getEntry(10, 4); + fail ("Expecting MatrixIndexException"); } catch (MatrixIndexException ex) { - ; + // expected } }
@@ -475,8 +455,7 @@ RealMatrix m = new RealMatrixImpl(matrixData); // One more with three rows, two columns double[][] matrixData2 = { {1d,2d}, {2d,5d}, {1d, 7d}}; - RealMatrix n = new RealMatrixImpl(); - n.setData(matrixData2); + RealMatrix n = new RealMatrixImpl(matrixData2); // Now multiply m by n RealMatrix p = m.multiply(n); assertEquals(2, p.getRowDimension()); @@ -652,24 +631,24 @@ }
/** extracts the l and u matrices from compact lu representation */ - protected void splitLU(RealMatrix lu, RealMatrix lower, RealMatrix upper) throws InvalidMatrixException { - if (!lu.isSquare() || !lower.isSquare() || !upper.isSquare() || - lower.getRowDimension() != upper.getRowDimension() - || lower.getRowDimension() != lu.getRowDimension()) { + protected void splitLU(RealMatrix lu, double[][] lowerData, double[][] upperData) throws InvalidMatrixException { + if (!lu.isSquare() || lowerData.length != lowerData[0].length || upperData.length != upperData[0].length || + lowerData.length != upperData.length + || lowerData.length != lu.getRowDimension()) { throw new InvalidMatrixException("incorrect dimensions"); } int n = lu.getRowDimension(); for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { if (j < i) { - lower.setEntry(i, j, lu.getEntry(i, j)); - upper.setEntry(i, j, 0d); + lowerData[i][j] = lu.getEntry(i, j); + upperData[i][j] = 0d; } else if (i == j) { - lower.setEntry(i, j, 1d); - upper.setEntry(i, j, lu.getEntry(i, j)); + lowerData[i][j] = 1d; + upperData[i][j] = lu.getEntry(i, j); } else { - lower.setEntry(i, j, 0d); - upper.setEntry(i, j, lu.getEntry(i, j)); + lowerData[i][j] = 0d; + upperData[i][j] = lu.getEntry(i, j); } } } @@ -681,21 +660,24 @@ throw new IllegalArgumentException("dimension mismatch"); } int n = matrix.getRowDimension(); - RealMatrix out = new RealMatrixImpl(n, n); + int m = matrix.getColumnDimension(); + double out[][] = new double[m][n]; for (int i = 0; i < n; i++) { - for (int j = 0; j < n; j++) { - out.setEntry(i, j, matrix.getEntry(permutation[i], j)); + for (int j = 0; j < m; j++) { + out[i][j] = matrix.getEntry(permutation[i], j); } } - return out; + return new RealMatrixImpl(out); }
/** Extracts l and u matrices from lu and verifies that matrix = l times u modulo permutation */ protected void verifyDecomposition(RealMatrix matrix, RealMatrix lu) throws Exception{ int n = matrix.getRowDimension(); - RealMatrix lower = new RealMatrixImpl(n, n); - RealMatrix upper = new RealMatrixImpl(n, n); - splitLU(lu, lower, upper); + double[][] lowerData = new double[n][n]; + double[][] upperData = new double[n][n]; + splitLU(lu, lowerData, upperData); + RealMatrix lower =new RealMatrixImpl(lowerData); + RealMatrix upper = new RealMatrixImpl(upperData); int[] permutation = ((RealMatrixImpl) matrix).getPermutation(); RealMatrix permuted = permuteRows(matrix, permutation); assertClose("lu decomposition does not work", permuted, lower.multiply(upper), normTolerance);
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-- Mark Diggory Open Source Software Developer Apache Jakarta Project http://jakarta.apache.org
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