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don't compute the expensive Q matrix until really needed 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@722476 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Luc Maisonobe 2008-12-02 14:41:47 +00:00
parent 25756255de
commit bcebd1a54f
1 changed files with 6 additions and 8 deletions
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14
src/java/org/apache/commons/math/linear/EigenDecompositionImpl.java
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@ -76,8 +76,8 @@ public class EigenDecompositionImpl implements EigenDecomposition {
/** Squared secondary diagonal of the tridiagonal matrix. */
private double[] squaredSecondary;
/** Orthogonal matrix of tridiagonal transformation. */
private RealMatrix orthoTridiag;
/** Transformer to tridiagonal (may be null if matrix is already tridiagonal). */
private TriDiagonalTransformer transformer;
/** Lower bound of spectra. */
private double lowerSpectra;
@ -232,7 +232,7 @@ public class EigenDecompositionImpl implements EigenDecomposition {
this.main = main;
this.secondary = secondary;
orthoTridiag = null;
transformer = null;
// pre-compute some elements
squaredSecondary = new double[secondary.length];
@ -518,7 +518,7 @@ public class EigenDecompositionImpl implements EigenDecomposition {
private void transformToTridiagonal(final RealMatrix matrix) {
// transform the matrix to tridiagonal
TriDiagonalTransformer transformer = new TriDiagonalTransformer(matrix);
transformer = new TriDiagonalTransformer(matrix);
main = transformer.getMainDiagonalRef();
secondary = transformer.getSecondaryDiagonalRef();
@ -529,8 +529,6 @@ public class EigenDecompositionImpl implements EigenDecomposition {
squaredSecondary[i] = s * s;
}
orthoTridiag = transformer.getQ();
}
/**
@ -1754,9 +1752,9 @@ public class EigenDecompositionImpl implements EigenDecomposition {
eigenvector[i] *= inv;
}
return (orthoTridiag == null) ?
return (transformer == null) ?
new RealVectorImpl(eigenvector, false) :
new RealVectorImpl(orthoTridiag.operate(eigenvector), false);
new RealVectorImpl(transformer.getQ().operate(eigenvector), false);
}