russell_lab 1.14.0

Scientific laboratory for linear algebra and numerical mathematics
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
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

use num_traits::{Num, NumCast};

/// Panics if two numbers are not approximately equal to each other
///
/// # Panics
///
/// 1. Will panic if NAN, INFINITY, or NEG_INFINITY is found
/// 2. Will panic if the absolute difference is greater than the tolerance
///
/// # Input
///
/// `a` -- Left value
/// `b` -- Right value
/// `tol: f64` -- Error tolerance: panic occurs if `|a - b| > tol`
///
/// # Examples
///
/// ## Accepts small error
///
/// ```
/// use russell_lab::approx_eq;
///
/// fn main() {
///     let a = 3.0000001;
///     let b = 3.0;
///     approx_eq(a, b, 1e-6);
/// }
/// ```
///
/// ## Panics on different value
///
/// ```should_panic
/// use russell_lab::approx_eq;
///
/// fn main() {
///     let a = 1.0;
///     let b = 2.0;
///     approx_eq(a, b, 1e-6);
/// }
/// ```
pub fn approx_eq<T>(a: T, b: T, tol: f64)
where
    T: Num + NumCast + Copy,
{
    let aa = a.to_f64().unwrap();
    let bb = b.to_f64().unwrap();
    if aa.is_nan() {
        panic!("the first number is NaN");
    }
    if bb.is_nan() {
        panic!("the second number is NaN");
    }
    if aa.is_infinite() {
        panic!("the first number is Inf");
    }
    if bb.is_infinite() {
        panic!("the second number is Inf");
    }
    let diff = f64::abs(aa - bb);
    if diff > tol {
        panic!("numbers are not approximately equal. diff = {:?}", diff);
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

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

    #[test]
    #[should_panic(expected = "the first number is NaN")]
    fn panics_on_nan_1() {
        approx_eq(f64::NAN, 2.5, 1e-1);
    }

    #[test]
    #[should_panic(expected = "the second number is NaN")]
    fn panics_on_nan_2() {
        approx_eq(2.5, f64::NAN, 1e-1);
    }

    #[test]
    #[should_panic(expected = "the first number is Inf")]
    fn panics_on_inf_1() {
        approx_eq(f64::INFINITY, 2.5, 1e-1);
    }

    #[test]
    #[should_panic(expected = "the second number is Inf")]
    fn panics_on_inf_2() {
        approx_eq(2.5, f64::INFINITY, 1e-1);
    }

    #[test]
    #[should_panic(expected = "the first number is Inf")]
    fn panics_on_inf_3() {
        approx_eq(f64::NEG_INFINITY, 2.5, 1e-1);
    }

    #[test]
    #[should_panic(expected = "the second number is Inf")]
    fn panics_on_inf_4() {
        approx_eq(2.5, f64::NEG_INFINITY, 1e-1);
    }

    #[test]
    #[should_panic(expected = "numbers are not approximately equal. diff = 0.5")]
    fn panics_on_different_values() {
        approx_eq(2.0, 2.5, 1e-1);
    }

    #[test]
    #[should_panic(expected = "numbers are not approximately equal. diff = 0.5")]
    fn panics_on_different_values_f32() {
        approx_eq(2f32, 2.5f32, 1e-1);
    }

    #[test]
    fn accepts_approx_equal_values() {
        let a = 2.0;
        let b = 2.02;
        let tol = 0.03;
        approx_eq(a, b, tol);
    }

    #[test]
    fn accepts_approx_equal_values_f32() {
        approx_eq(2f32, 2.02f32, 0.03);
    }
}