Scilab Function
Last update : April 1993

proj - projection

### Calling Sequence

  `P = proj(X1,X2)`

### Parameters

- `X1,X2`: two real matrices with equal number of columns
- `P`: real projection matrix (`P^2=P`)

### Description

`P` is the projection on `X2` parallel to `X1`.

### Examples

    X1=rand(5,2);X2=rand(5,3);
    P=proj(X1,X2);
    norm(P^2-P,1)
    trace(P)    // This is dim(X2)
    [Q,M]=fullrf(P);
    svd([Q,X2])   // span(Q) = span(X2)

### See Also

`projspec`, `orth`, `fullrf`,

### Author

F. D.; ;