QR decomposition: Difference between revisions

Content added Content deleted
m (Minor code improvement.)
m (Minor code improvements.)
Line 3,315: Line 3,315:
for ( int k = 0; k < columnCount && k < rowCount - 1; k++ ) {
for ( int k = 0; k < columnCount && k < rowCount - 1; k++ ) {
Matrix vectorE = new Matrix( new double[rowCount][1] );
Matrix vectorE = new Matrix(rowCount, 1);
z1 = z.minor(k);
z1 = z.minor(k);
Matrix vectorX = z1.column(k);
Matrix vectorX = z1.column(k);
Line 3,326: Line 3,326:
vectorE.setEntry(i, 0, ( i == k ) ? 1 : 0);
vectorE.setEntry(i, 0, ( i == k ) ? 1 : 0);
}
}
vectorE = vectorE.scalarMultiply(magnitudeX).add(vectorX);
vectorE = vectorE.scalarMultiply(magnitudeX).add(vectorX).unit();
vectorE = vectorE.unit();
versionsOfQ.add(householderFactor(vectorE));
versionsOfQ.add(householderFactor(vectorE));
z = versionsOfQ.get(k).multiply(z1);
z = versionsOfQ.get(k).multiply(z1);
Line 3,348: Line 3,347:
final int size = aVector.size();
final int size = aVector.size();
double[][] newData = new double[size][size];
Matrix result = new Matrix(size, size);
for ( int i = 0; i < size; i++ ) {
for ( int i = 0; i < size; i++ ) {
for ( int j = 0; j < size; j++ ) {
for ( int j = 0; j < size; j++ ) {
newData[i][j] = -2 * aVector.getEntry(i, 0) * aVector.getEntry(j, 0);
result.setEntry(i, j, -2 * aVector.getEntry(i, 0) * aVector.getEntry(j, 0));
}
}
}
}
for ( int i = 0; i < size; i++ ) {
for ( int i = 0; i < size; i++ ) {
newData[i][i] += 1;
result.setEntry(i, i, result.getEntry(i, i) + 1.0);
}
}
return new Matrix(newData);
return result;
}
}
Line 3,411: Line 3,410:
}
}
public Matrix(int aRows, int aCols) {
public Matrix(int aRowCount, int aColumnCount) {
this( new double[aRows][aCols] );
this( new double[aRowCount][aColumnCount] );
}
}


Line 3,469: Line 3,468:
}
}
public Matrix column(int aColumn) {
public Matrix column(int aIndex) {
Matrix result = new Matrix(rowCount, 1);
Matrix result = new Matrix(rowCount, 1);
for ( int i = 0; i < rowCount; i++ ) {
for ( int i = 0; i < rowCount; i++ ) {
result.setEntry(i, 0, data[i][aColumn]);
result.setEntry(i, 0, data[i][aIndex]);
}
}
return result;
return result;
Line 3,483: Line 3,482:
Matrix result = new Matrix(rowCount, columnCount);
Matrix result = new Matrix(rowCount, columnCount);
for ( int i = 0; i < data.length; i++ ) {
for ( int i = 0; i < rowCount; i++ ) {
result.data[i][0] = data[i][0] * aValue;
result.data[i][0] = data[i][0] * aValue;
}
}
Line 3,496: Line 3,495:
final double magnitude = magnitude();
final double magnitude = magnitude();
Matrix result = new Matrix(rowCount, columnCount);
Matrix result = new Matrix(rowCount, columnCount);
for ( int i = 0; i < data.length; i++ ) {
for ( int i = 0; i < rowCount; i++ ) {
result.data[i][0] = data[i][0] / magnitude;
result.data[i][0] = data[i][0] / magnitude;
}
}
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throw new IllegalArgumentException("Incompatible matrix dimensions.");
throw new IllegalArgumentException("Incompatible matrix dimensions.");
}
}
return data.length;
return rowCount;
}
}
Line 3,532: Line 3,531:
}
}
public double getEntry(int aRow, int aCol) {
public double getEntry(int aRow, int aColumn) {
return data[aRow][aCol];
return data[aRow][aColumn];
}
}
public void setEntry(int aRow, int aCol, double aValue) {
public void setEntry(int aRow, int aColumn, double aValue) {
data[aRow][aCol] = aValue;
data[aRow][aColumn] = aValue;
}
}
Retrieved from "https://rosettacode.org/wiki/QR_decomposition"