quad 0.1.2

Quadrature integration
Documentation 
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use crate::constants::*;

pub fn semi_infinite_function<F>(f: &F, x: f64, start: f64, infty: f64) -> Vec<f64>
where
    F: Fn(f64) -> Vec<f64> + ?Sized,
{
    if x < UFLOW.sqrt() {
        return vec![0.0; f(0.0).len()];
    }
    let sgn = if infty.is_sign_positive() { 1.0 } else { -1.0 };
    let z = start + sgn * (1.0 - x) / x;
    let mut res: Vec<f64> = f(z);
    div(&mut res, sgn * x * x);
    res
}

pub fn double_infinite_function<F>(f: &F, x: f64) -> Vec<f64>
where
    F: Fn(f64) -> Vec<f64> + ?Sized,
{
    if x.abs() < UFLOW.sqrt() {
        return vec![0.0; f(0.0).len()];
    }
    let z = (1.0 - x.abs()) / x;
    let mut res: Vec<f64> = f(z);
    div(&mut res, x * x);
    res
}

/*
pub fn semi_infinite_function_par<F>(f : &F, x : f64, start : f64, infty : f64) -> [f64;N]
    where F : Fn(f64) -> [f64;N] {
    if x < UFLOW.sqrt() { return [0.0;N] }
    let sgn = if infty.is_sign_positive() { 1.0 } else { - 1.0};
    let z = start + sgn * (1.0 - x) / x;
    let mut res: [f64;N] = f(z);
    div( &mut res, sgn * x * x);
    res
}

pub fn double_infinite_function_par<const N : usize,F>(f : &F, x : f64) -> [f64;N]
    where F : Fn(f64) -> [f64;N] {
    if x.abs() < UFLOW.sqrt() { return [0.0;N] }
    let z = (1.0 - x.abs()) / x;
    let mut res: [f64;N] = f(z);
    div( &mut res,  x * x);
    res
}




 */

pub fn div(arr: &mut [f64], scalar: f64) {
    for k in 0..arr.len() {
        arr[k] /= scalar;
    }
}