Function rgsl::interpolation::bsearch

pub fn bsearch(
    x_array: &[f64], 
    x: f64, 
    index_lo: usize, 
    index_hi: usize
) -> usize

This function returns the index i of the array x_array such that x_array[i] <= x < x_array[i+1]. The index is searched for in the range [index_lo,index_hi].