Function linspace 

pub fn linspace<F>(a: F, b: F, n: usize) -> Linspace<F> 
where
    F: Float,

Return an iterator of evenly spaced floats.

The Linspace has n elements from a to b (inclusive).

The iterator element type is F, where F must implement Float, e.g. f32 or f64.

Panics if converting n - 1 to type F fails.