Author: luc
Date: Sun Sep 28 08:59:14 2008
New Revision: 699846
URL: http://svn.apache.org/viewvc?rev=699846&view=rev
Log:
slight optimization:
cached pointers to row vectors from double arrays
wherever the same row was used in a loop, to avoid
double index computation/range check
Modified:
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/linear/BiDiagonalTransformer.java
Modified:
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/linear/BiDiagonalTransformer.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/linear/BiDiagonalTransformer.java?rev=699846&r1=699845&r2=699846&view=diff
==============================================================================
---
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/linear/BiDiagonalTransformer.java
(original)
+++
commons/proper/math/branches/MATH_2_0/src/java/org/apache/commons/math/linear/BiDiagonalTransformer.java
Sun Sep 28 08:59:14 2008
@@ -59,10 +59,9 @@
/**
* Build the transformation to bi-diagonal shape of a matrix.
- * @param matrix The matrix to transform.
+ * @param matrix the matrix to transform.
*/
- public BiDiagonalTransformer(RealMatrix matrix)
- throws InvalidMatrixException {
+ public BiDiagonalTransformer(RealMatrix matrix) {
final int m = matrix.getRowDimension();
final int n = matrix.getColumnDimension();
@@ -148,12 +147,15 @@
final int n = householderVectors[0].length;
double[][] bData = new double[m][n];
for (int i = 0; i < main.length; ++i) {
- bData[i][i] = main[i];
- if (i < main.length - 1) {
- if (m < n) {
- bData[i + 1][i] = secondary[i];
- } else {
- bData[i][i + 1] = secondary[i];
+ double[] bDataI = bData[i];
+ bDataI[i] = main[i];
+ if (m < n) {
+ if (i > 0) {
+ bDataI[i - 1] = secondary[i - 1];
+ }
+ } else {
+ if (i < main.length - 1) {
+ bDataI[i + 1] = secondary[i];
}
}
}
@@ -276,45 +278,45 @@
final double c = householderVectors[i][k];
xNormSqr += c * c;
}
- final double a = (householderVectors[k][k] > 0) ?
-Math.sqrt(xNormSqr) : Math.sqrt(xNormSqr);
+ final double[] hK = householderVectors[k];
+ final double a = (hK[k] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
main[k] = a;
if (a != 0.0) {
- householderVectors[k][k] -= a;
+ hK[k] -= a;
for (int j = k + 1; j < n; ++j) {
double alpha = 0;
for (int i = k; i < m; ++i) {
- final double[] uvI = householderVectors[i];
- alpha -= uvI[j] * uvI[k];
+ final double[] hI = householderVectors[i];
+ alpha -= hI[j] * hI[k];
}
alpha /= a * householderVectors[k][k];
for (int i = k; i < m; ++i) {
- final double[] uvI = householderVectors[i];
- uvI[j] -= alpha * uvI[k];
+ final double[] hI = householderVectors[i];
+ hI[j] -= alpha * hI[k];
}
}
}
if (k < n - 1) {
//zero-out a row
- final double[] uvK = householderVectors[k];
xNormSqr = 0;
for (int j = k + 1; j < n; ++j) {
- final double c = uvK[j];
+ final double c = hK[j];
xNormSqr += c * c;
}
- final double b = (uvK[k + 1] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
+ final double b = (hK[k + 1] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
secondary[k] = b;
if (b != 0.0) {
- uvK[k + 1] -= b;
+ hK[k + 1] -= b;
for (int i = k + 1; i < m; ++i) {
- final double[] uvI = householderVectors[i];
+ final double[] hI = householderVectors[i];
double beta = 0;
for (int j = k + 1; j < n; ++j) {
- beta -= uvI[j] * uvK[j];
+ beta -= hI[j] * hK[j];
}
- beta /= b * uvK[k + 1];
+ beta /= b * hK[k + 1];
for (int j = k + 1; j < n; ++j) {
- uvI[j] -= beta * uvK[j];
+ hI[j] -= beta * hK[j];
}
}
}
@@ -335,50 +337,51 @@
for (int k = 0; k < m; k++) {
//zero-out a row
- final double[] uvK = householderVectors[k];
+ final double[] hK = householderVectors[k];
double xNormSqr = 0;
for (int j = k; j < n; ++j) {
- final double c = uvK[j];
+ final double c = hK[j];
xNormSqr += c * c;
}
- final double a = (uvK[k] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
+ final double a = (hK[k] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
main[k] = a;
if (a != 0.0) {
- uvK[k] -= a;
+ hK[k] -= a;
for (int i = k + 1; i < m; ++i) {
- final double[] uvI = householderVectors[i];
+ final double[] hI = householderVectors[i];
double alpha = 0;
for (int j = k; j < n; ++j) {
- alpha -= uvI[j] * uvK[j];
+ alpha -= hI[j] * hK[j];
}
alpha /= a * householderVectors[k][k];
for (int j = k; j < n; ++j) {
- uvI[j] -= alpha * uvK[j];
+ hI[j] -= alpha * hK[j];
}
}
}
if (k < m - 1) {
//zero-out a column
+ final double[] hKp1 = householderVectors[k + 1];
xNormSqr = 0;
for (int i = k + 1; i < m; ++i) {
final double c = householderVectors[i][k];
xNormSqr += c * c;
}
- final double b = (householderVectors[k + 1][k] > 0) ?
-Math.sqrt(xNormSqr) : Math.sqrt(xNormSqr);
+ final double b = (hKp1[k] > 0) ? -Math.sqrt(xNormSqr) :
Math.sqrt(xNormSqr);
secondary[k] = b;
if (b != 0.0) {
- householderVectors[k + 1][k] -= b;
+ hKp1[k] -= b;
for (int j = k + 1; j < n; ++j) {
double beta = 0;
for (int i = k + 1; i < m; ++i) {
- final double[] uvI = householderVectors[i];
- beta -= uvI[j] * uvI[k];
+ final double[] hI = householderVectors[i];
+ beta -= hI[j] * hI[k];
}
- beta /= b * householderVectors[k + 1][k];
+ beta /= b * hKp1[k];
for (int i = k + 1; i < m; ++i) {
- final double[] uvI = householderVectors[i];
- uvI[j] -= beta * uvI[k];
+ final double[] hI = householderVectors[i];
+ hI[j] -= beta * hI[k];
}
}
}
