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

## 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>]
-------------------------------
```