use std::f64::consts::E;
pub fn brown_and_dennis(x: &[f64], m: usize) -> f64 {
if x.len() != 4 {
panic!("input dimension must be 4");
}
if m < x.len() {
panic!("number of auxiliary function must be at least n");
}
let x1 = x[0];
let x2 = x[1];
let x3 = x[2];
let x4 = x[3];
let mut res = 0.;
for i in 1..(m + 1) {
let t = (i as f64) / 5.;
let f = (x1 + t * x2 - E.powf(t)).powi(2) + (x3 + x4 * t.sin() - t.cos()).powi(2);
res += f.powi(2);
}
res
}
pub fn init() -> Vec<f64> {
vec![25., 5., -1., -1.]
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_brown_and_dennis() {
let x = init();
let val = brown_and_dennis(&x, 10);
assert!(val.is_finite());
}
}