Function interpn_serial 

pub fn interpn_serial<T: Float>(
    grids: &[&[T]],
    vals: &[T],
    obs: &[&[T]],
    out: &mut [T],
    method: GridInterpMethod,
    assume_grid_kind: Option<GridKind>,
    linearize_extrapolation: bool,
    check_bounds_with_atol: Option<T>,
) -> Result<(), &'static str>

Single-threaded, non-allocating variant of interpn available without par feature.