math-test-functions 0.5.2

A collection of non linear functions for testing optimisation algorithms
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41

//! Lampinen Simplified test function

use ndarray::Array1;

/// Simplified Lampinen test problem (unconstrained version)
/// f(x) = sum(5*x\[i\]) - sum(x\[i\]^2) for i in 0..4, - sum(x\[j\]) for j in 4..
pub fn lampinen_simplified(x: &Array1<f64>) -> f64 {
    let mut sum = 0.0;

    // First 4 variables: 5*x[i] - x[i]^2
    for i in 0..4.min(x.len()) {
        sum += 5.0 * x[i] - x[i] * x[i];
    }

    // Remaining variables: -x[j]
    for i in 4..x.len() {
        sum -= x[i];
    }

    -sum // Minimize negative (i.e., maximize original)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn handles_short_vectors() {
        let x = Array1::from(vec![1.0, 2.0]);
        let value = lampinen_simplified(&x);
        assert!(value.is_finite());
    }

    #[test]
    fn handles_tail_variables() {
        let x = Array1::from(vec![1.0, 2.0, 3.0, 4.0, 5.0]);
        let value = lampinen_simplified(&x);
        assert!(value.is_finite());
        assert_eq!(value, -15.0);
    }
}