Consider exposing stored x and y values

[ivan-aksamentov]

When working on an iterative methods when data needs to be modified and interpolated, there's 2 choices:

• keep a copy of the original data around and also create and interp object
• keep only data and create interp object every time interpolation is needed

Both cases waste memoty and second also wastes CPU cycles.

It would be nice if we could have access to the original data, and mutable access would be amazing.

[jonasBoss]

you can use Interp1D::new_unchecked(x.view(), y.view(), ...) if you know that the data is valid. This is basically free and you don't need to copy stuff.

[jonasBoss]

fn main() {
    let x = array![1.0,2.0,3.0,4.0];
    let mut y = array![5.0,4.0,4.5,6.0];

    let interp = Interp1D::builder(y.view()).x(x.view()).build(); // this causes validation
    
    y[0] = 6.0;
    // changing y does not invalidate the data so we can use new_unchecked
    let interp = Interp1D::new_unchecked(x.view(), y.view(), Linear::new().extrapolate(true));
}