# ApCoCoA-1:Num.LeastSquaresQR

From ApCoCoAWiki

## Num.LeastSquaresQR

Computes the least squares solution of the linear system of equations `Ax=b`.

### Syntax

Num.LeastSquaresQR(Mat:MAT, Vec:MAT):LIST

### 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.

This command computes the least squares solution of the linear system of equations `Ax=b`, if there is no exact solution. The matrix `Mat` must have the same number of rows as `Vec`.

The QR decomposition of `Mat` is used to find the solution.

@param

*Mat*Matrix`A`of the linear system of equations.@param

*Vec*Vector`B`as a matrix.@return The least squares solution to

`Ax=b`.

#### Example

Dec(Num.LeastSquaresQR([[1,1],[0,1],[1,1]],[[0],[1],[0]]),2); -- CoCoAServer: computing Cpu Time = 0 ------------------------------- [<quotes>-0.99</quotes>, <quotes>1</quotes>] -------------------------------

### See also