QRP

java.lang.Object
- no.uib.cipr.matrix.QRP

```
public class QRP
extends java.lang.Object
```
Computes QR decompositions with column pivoting: A*P = Q*R where A(m,n), Q(m,m), and R(m,n), more generally: A*P = [Q1 Q2] * [R11, R12; 0 R22] and R22 elements are negligible.

Constructor Summary

Constructors
Constructor Description

QRP(int m, int n)
Constructs an empty QR decomposition

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`QRP`	`factor(Matrix A)`	Executes a QR factorization for the given matrix.
`static QRP`	`factorize(Matrix A)`	Convenience method to compute a QR decomposition
`Matrix`	`getP()`	Returns the column pivoting matrix.
`int[]`	`getPVector()`	Returns the column pivoting vector.
`DenseMatrix`	`getQ()`	Returns the orthogonal matrix
`DenseMatrix`	`getR()`	Returns the upper triangular factor
`int`	`getRank()`	Returns the rank of the factored matrix

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - QRP
```
public QRP(int m,
           int n)
```
    Constructs an empty QR decomposition
    
    Parameters:
    
    m - the number of rows.
    
    n - the number of columns.
- Method Detail
  - factorize
```
public static QRP factorize(Matrix A)
```
    Convenience method to compute a QR decomposition
    
    Parameters:
    
    A - the matrix to decompose (not modified)
    
    Returns:
    
    Newly allocated decomposition
  - factor
```
public QRP factor(Matrix A)
```
    Executes a QR factorization for the given matrix.
    
    Parameters:
    
    A - the matrix to be factored (not modified)
    
    Returns:
    
    the factorization object
  - getR
```
public DenseMatrix getR()
```
    Returns the upper triangular factor
  - getQ
```
public DenseMatrix getQ()
```
    Returns the orthogonal matrix
  - getPVector
```
public int[] getPVector()
```
    Returns the column pivoting vector. This function is cheaper than getP().
  - getP
```
public Matrix getP()
```
    Returns the column pivoting matrix. This function allocates a new Matrix to be returned, a more cheap option is tu use getPVector().
  - getRank
```
public int getRank()
```
    Returns the rank of the factored matrix