ps_ecc/polynomial/methods/
eval_at.rs

1use crate::Polynomial;
2
3impl Polynomial {
4    /// Evaluates this polynomial at the given point.
5    #[must_use]
6    pub fn eval_at(&self, x: u8) -> u8 {
7        Self::eval_coefficients_at(self.coefficients(), x)
8    }
9}
10
11#[cfg(test)]
12mod tests {
13    use crate::Polynomial;
14
15    /// Asserts that `eval_at` matches `eval_coefficients_at` for all x in 0..=255.
16    fn assert_exhaustive(p: &Polynomial) {
17        for x in 0..=255u8 {
18            assert_eq!(
19                p.eval_at(x),
20                Polynomial::eval_coefficients_at(p.coefficients(), x)
21            );
22        }
23    }
24
25    #[test]
26    fn zero_polynomial() {
27        assert_exhaustive(&Polynomial::default());
28    }
29
30    #[test]
31    fn constant_polynomial() {
32        let mut p = Polynomial::default();
33
34        p.set(0, 42);
35
36        assert_exhaustive(&p);
37
38        let mut p = Polynomial::default();
39
40        p.set(0, 255);
41
42        assert_exhaustive(&p);
43
44        let mut p = Polynomial::default();
45
46        p.set(0, 1);
47
48        assert_exhaustive(&p);
49    }
50
51    #[test]
52    fn linear_polynomial() {
53        let mut p = Polynomial::default();
54
55        p.set(0, 5);
56        p.set(1, 3);
57
58        assert_exhaustive(&p);
59
60        let mut p = Polynomial::default();
61
62        p.set(0, 0);
63        p.set(1, 1);
64
65        assert_exhaustive(&p);
66
67        let mut p = Polynomial::default();
68
69        p.set(0, 255);
70        p.set(1, 255);
71
72        assert_exhaustive(&p);
73    }
74
75    #[test]
76    fn quadratic_polynomial() {
77        let mut p = Polynomial::default();
78
79        p.set(0, 1);
80        p.set(1, 0);
81        p.set(2, 1);
82
83        assert_exhaustive(&p);
84
85        let mut p = Polynomial::default();
86
87        p.set(0, 0);
88        p.set(1, 0);
89        p.set(2, 1);
90
91        assert_exhaustive(&p);
92
93        let mut p = Polynomial::default();
94
95        p.set(0, 255);
96        p.set(1, 128);
97        p.set(2, 64);
98
99        assert_exhaustive(&p);
100    }
101
102    #[test]
103    fn cubic_polynomial() {
104        let mut p = Polynomial::default();
105
106        p.set(0, 0x12);
107        p.set(1, 0x34);
108        p.set(2, 0x56);
109        p.set(3, 0x78);
110
111        assert_exhaustive(&p);
112
113        let mut p = Polynomial::default();
114
115        p.set(0, 1);
116        p.set(1, 1);
117        p.set(2, 1);
118        p.set(3, 1);
119
120        assert_exhaustive(&p);
121
122        let mut p = Polynomial::default();
123
124        p.set(3, 1);
125
126        assert_exhaustive(&p);
127    }
128
129    #[test]
130    fn high_degree_polynomial() {
131        let mut p = Polynomial::default();
132
133        for i in 0..8 {
134            p.set(i, i + 1);
135        }
136
137        assert_exhaustive(&p);
138
139        let mut p = Polynomial::default();
140
141        p.set(7, 1);
142
143        assert_exhaustive(&p);
144    }
145
146    #[test]
147    fn sparse_polynomial() {
148        let mut p = Polynomial::default();
149
150        p.set(0, 1);
151        p.set(4, 1);
152
153        assert_exhaustive(&p);
154
155        let mut p = Polynomial::default();
156
157        p.set(1, 1);
158        p.set(3, 1);
159
160        assert_exhaustive(&p);
161    }
162
163    #[test]
164    fn all_coefficients_max() {
165        let mut p = Polynomial::default();
166
167        p.set(0, 255);
168        p.set(1, 255);
169        p.set(2, 255);
170        p.set(3, 255);
171
172        assert_exhaustive(&p);
173    }
174
175    #[test]
176    fn max_degree_monomial() {
177        let mut p = Polynomial::default();
178
179        p.set(Polynomial::MAX_DEGREE, 1);
180
181        assert_exhaustive(&p);
182    }
183
184    #[test]
185    fn max_degree_all_ones() {
186        let mut p = Polynomial::default();
187
188        for i in 0..=Polynomial::MAX_DEGREE {
189            p.set(i, 1);
190        }
191
192        assert_exhaustive(&p);
193    }
194
195    #[test]
196    fn max_degree_all_max() {
197        let mut p = Polynomial::default();
198
199        for i in 0..=Polynomial::MAX_DEGREE {
200            p.set(i, 255);
201        }
202
203        assert_exhaustive(&p);
204    }
205}
ps_ecc/polynomial/methods/eval_at.rs

ps_ecc/polynomial/methods/
eval_at.rs
