givens

Scilab Function
Last update : April 1993

givens - Givens transformation

### Calling Sequence

  `U=givens(xy)`
  `U=givens(x,y)`
  `[U,c]=givens(xy)`
  `[U,c]=givens(x,y)`

### Parameters

- `x,y`: two real or complex numbers
- `xy`: real or complex size 2 column vector
- `U`: 2x2 unitary matrix
- `c`: real or complex size 2 column vector

### Description

`U = givens(x, y)` or `U = givens(xy)` with `xy = [x;y]` returns a `2`x`2` unitary matrix `U` such that:

`U*xy=[r;0]=c`.

Note that `givens(x,y)` and `givens([x;y])` are equivalent.

### Examples

    A=[3,4;5,6];
    U=givens(A(:,1));
    U*A

### See Also

`qr`,