# Difference between revisions of "ApCoCoA-1:Num.QR"

From ApCoCoAWiki

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− | [< | + | [<quotes>2.999</quotes>, <quotes>3.999</quotes>, <quote>4.999</quotes>] |

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## Revision as of 08:16, 7 July 2009

## Num.QR

Computes the QR-decomposition of a matrix.

### Syntax

Num.QR(A:MAT):[Q:MAT,R:MAT]

### Description

*Please note:* The function(s) explained on this page is/are using the *ApCoCoAServer*. You will have to start the ApCoCoAServer in order to use it/them.

Calculates the QR decomposition of a matrix using Lapack.

@param

*A*Matrix A@return An orthogonal matrix Q and an upper-right triangular matrix R such that Q*R=A.

#### Example

Points:=Mat([[1,2,3],[2,3,4],[3,4,5]]); QR := Num.QR(Points); Dec(QR[1]*QR[2],3); -- CoCoAServer: computing Cpu Time = 0 ------------------------------- Mat([ [<quotes>0.999</quotes>, <quotes>1.999</quotes>, <quote>2.999</quotes>], [<quotes>1.999</quotes>, <quotes>2.999</quotes>, <quote>3.999</quotes>], [<quotes>2.999</quotes>, <quotes>3.999</quotes>, <quote>4.999</quotes>] ]) -------------------------------

### See also