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trigger an error when the transform is not invertible 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@777263 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Luc Maisonobe 2009-05-21 21:21:15 +00:00
parent 1ed2b9afc5
commit 7fc6ee7ff4
1 changed files with 12 additions and 8 deletions
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20
src/java/org/apache/commons/math/ode/NordsieckTransformer.java
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@ -24,6 +24,7 @@ import org.apache.commons.math.fraction.BigFraction;
import org.apache.commons.math.linear.DefaultFieldMatrixPreservingVisitor;
import org.apache.commons.math.linear.FieldMatrix;
import org.apache.commons.math.linear.FieldMatrixImpl;
import org.apache.commons.math.linear.InvalidMatrixException;
import org.apache.commons.math.linear.RealMatrix;
import org.apache.commons.math.linear.RealMatrixImpl;
import org.apache.commons.math.linear.decomposition.FieldDecompositionSolver;
@ -100,15 +101,18 @@ public class NordsieckTransformer implements Serializable {
/**
* Build a transformer for a specified order.
* <p>states considered are y<sub>k-p</sub>, y<sub>k-(p+1)</sub> ...
* <p>States considered are y<sub>k-p</sub>, y<sub>k-(p+1)</sub> ...
* y<sub>k-(q-1)</sub> and scaled derivatives considered are
* h y'<sub>k-r</sub>, h y'<sub>k-(r+1)</sub> ... h y'<sub>k-(s-1)</sub>
* h y'<sub>k-r</sub>, h y'<sub>k-(r+1)</sub> ... h y'<sub>k-(s-1)</sub><\p>
* @param p start state index offset in multistep form
* @param q end state index offset in multistep form
* @param r start state derivative index offset in multistep form
* @param s end state derivative index offset in multistep form
* @exception InvalidMatrixException if the selected indices ranges define a
* non-invertible transform (this typically happens when p == q)
*/
public NordsieckTransformer(final int p, final int q, final int r, final int s) {
public NordsieckTransformer(final int p, final int q, final int r, final int s)
throws InvalidMatrixException {
// from Nordsieck to multistep
final FieldMatrix<BigFraction> bigNtoM = buildNordsieckToMultistep(p, q, r, s);
@ -128,7 +132,7 @@ public class NordsieckTransformer implements Serializable {
/**
* Build the transform from Nordsieck to multistep.
* <p>states considered are y<sub>k-p</sub>, y<sub>k-(p+1)</sub> ...
* <p>States considered are y<sub>k-p</sub>, y<sub>k-(p+1)</sub> ...
* y<sub>k-(q-1)</sub> and scaled derivatives considered are
* h y'<sub>k-r</sub>, h y'<sub>k-(r+1)</sub> ... h y'<sub>k-(s-1)</sub>
* @param p start state index offset in multistep form
@ -163,10 +167,10 @@ public class NordsieckTransformer implements Serializable {
for (int l = r; l < s; ++l) {
// handle previous state scaled derivative h y'<sub>(k-l)</sub>
// the following expressions are direct applications of Taylor series
// h y'<sub>k-1</sub>: [ 0 1 -2 3 -4 5 ...]
// h y'<sub>k-2</sub>: [ 0 1 -4 6 -8 10 ...]
// h y'<sub>k-3</sub>: [ 0 1 -6 9 -12 15 ...]
// h y'<sub>k-4</sub>: [ 0 1 -8 12 -16 20 ...]
// h y'<sub>k-1</sub>: [ 0 1 -2 3 -4 5 ...]
// h y'<sub>k-2</sub>: [ 0 1 -4 12 -32 80 ...]
// h y'<sub>k-3</sub>: [ 0 1 -6 27 -108 405 ...]
// h y'<sub>k-4</sub>: [ 0 1 -8 48 -256 1280 ...]
final BigFraction[] row = array[i++];
final BigInteger factor = BigInteger.valueOf(-l);
row[0] = BigFraction.ZERO;