sphrs 0.2.2

Spherical harmonics and solid harmonics
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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270

// Copyright 2018-2023 Stefan Kroboth
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

use crate::SphrsFloat;

/// Definition of coordinates
///
/// Coordinates used in sphrs must implement this trait.
pub trait SHCoordinates<T>: Sized {
    /// Return `theta` (spherical coordinates)
    fn theta(&self) -> T;
    /// Return `phi` (spherical coordinates)
    fn phi(&self) -> T;
    /// Return radus `r` (spherical coordinates)
    fn r(&self) -> T;
    /// Return `x` (Cartesian coordinates)
    fn x(&self) -> T;
    /// Return `y` (Cartesian coordinates)
    fn y(&self) -> T;
    /// Return `z` (Cartesian coordinates)
    fn z(&self) -> T;
    /// Return `cos(theta)`
    fn theta_cos(&self) -> T;
}

/// Representation of coordinates.
///
/// Generic over floats. Can be created with [`cartesian`](`Coordinates::cartesian`) (Cartesian
/// coordinates) or [`spherical`](`Coordinates::spherical`) (spherical coordinates).
#[derive(Default, Clone, Debug)]
pub struct Coordinates<T> {
    /// radius (spherical coordinates)
    r: T,
    /// theta (spherical coordinates)
    theta: T,
    /// phi (spherical coordinates)
    phi: T,
    /// x (cartesian coordinates)
    x: T,
    /// y (cartesian coordinates)
    y: T,
    /// z (cartesian coordinates)
    z: T,
    /// cos(theta)
    theta_cos: T,
}

impl<T> Coordinates<T>
where
    T: SphrsFloat,
{
    /// Create `Coordinates` struct from Cartesian coordinates
    ///
    /// # Example
    ///
    /// ```
    /// # use sphrs::Coordinates;
    /// let coords = Coordinates::cartesian(1.0f64, 0.5, 12.0);
    /// ```
    pub fn cartesian(x: T, y: T, z: T) -> Self {
        let r = (x.powi(2) + y.powi(2) + z.powi(2)).sqrt();
        let theta = (z / r).acos();
        let phi = y.atan2(x);

        let theta_cos = theta.cos();
        Coordinates {
            r,
            theta,
            phi,
            x,
            y,
            z,
            theta_cos,
        }
    }

    /// Create `Coordinates` struct from spherical coordinates
    ///
    /// # Example
    ///
    /// ```
    /// # use sphrs::Coordinates;
    /// let coords = Coordinates::spherical(1.0f64, 0.5, 0.9);
    /// ```
    pub fn spherical(r: T, theta: T, phi: T) -> Self {
        let x = r * theta.sin() * phi.cos();
        let y = r * theta.sin() * phi.sin();
        let theta_cos = theta.cos();
        let z = r * theta_cos;
        Coordinates {
            r,
            theta,
            phi,
            x,
            y,
            z,
            theta_cos,
        }
    }
}

impl<T> SHCoordinates<T> for Coordinates<T>
where
    T: SphrsFloat,
{
    /// Return angle `theta`
    #[inline(always)]
    fn theta(&self) -> T {
        self.theta
    }

    /// Return angle `phi`
    #[inline(always)]
    fn phi(&self) -> T {
        self.phi
    }

    /// Return radius `r`
    #[inline(always)]
    fn r(&self) -> T {
        self.r
    }

    /// Return coordinate `x`
    #[inline(always)]
    fn x(&self) -> T {
        self.x
    }

    /// Return coordinate `y`
    #[inline(always)]
    fn y(&self) -> T {
        self.y
    }

    /// Return coordinate `z`
    #[inline(always)]
    fn z(&self) -> T {
        self.z
    }

    /// Return `cos(theta)`
    #[inline(always)]
    fn theta_cos(&self) -> T {
        self.theta_cos
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use approx::assert_relative_eq;
    use quickcheck_macros::quickcheck;

    #[derive(Debug, Copy, Clone)]
    struct Radius(f64);

    impl quickcheck::Arbitrary for Radius {
        fn arbitrary(g: &mut quickcheck::Gen) -> Self {
            loop {
                let val = f64::arbitrary(g) % 100000.0;
                if !val.is_nan() && val.is_finite() {
                    return Radius(val);
                }
            }
        }
    }

    #[derive(Debug, Copy, Clone)]
    struct Angle(f64);

    impl quickcheck::Arbitrary for Angle {
        fn arbitrary(g: &mut quickcheck::Gen) -> Self {
            loop {
                let val = f64::arbitrary(g) % 2.0 * std::f64::consts::PI;
                if !val.is_nan() && val.is_finite() {
                    return Angle(val);
                }
            }
        }
    }

    #[derive(Debug, Copy, Clone)]
    struct Cartesian(f64);

    impl quickcheck::Arbitrary for Cartesian {
        fn arbitrary(g: &mut quickcheck::Gen) -> Self {
            loop {
                let val = f64::arbitrary(g) % 100000.0;
                if !val.is_nan() && val.is_finite() {
                    return Cartesian(val);
                }
            }
        }
    }

    #[quickcheck]
    fn shcoordinates_spherical_f64(r: Radius, theta: Angle, phi: Angle) {
        let r = r.0;
        let theta = theta.0;
        let phi = phi.0;
        let coords = Coordinates::spherical(r, theta, phi);
        assert_relative_eq!(coords.r(), r);
        assert_relative_eq!(coords.theta(), theta);
        assert_relative_eq!(coords.phi(), phi);
        assert_relative_eq!(coords.x(), r * theta.sin() * phi.cos());
        assert_relative_eq!(coords.y(), r * theta.sin() * phi.sin());
        assert_relative_eq!(coords.z(), r * theta.cos());
        assert_relative_eq!(coords.theta_cos(), theta.cos());
    }

    #[quickcheck]
    fn shcoordinates_spherical_f32(r: Radius, theta: Angle, phi: Angle) {
        let r = r.0 as f32;
        let theta = theta.0 as f32;
        let phi = phi.0 as f32;
        let coords = Coordinates::spherical(r, theta, phi);
        assert_relative_eq!(coords.r(), r);
        assert_relative_eq!(coords.theta(), theta);
        assert_relative_eq!(coords.phi(), phi);
        assert_relative_eq!(coords.x(), r * theta.sin() * phi.cos());
        assert_relative_eq!(coords.y(), r * theta.sin() * phi.sin());
        assert_relative_eq!(coords.z(), r * theta.cos());
        assert_relative_eq!(coords.theta_cos(), theta.cos());
    }

    #[quickcheck]
    fn shcoordinates_cartesian_f64(x: Cartesian, y: Cartesian, z: Cartesian) {
        let x = x.0;
        let y = y.0;
        let z = z.0;
        let r = (x.powi(2) + y.powi(2) + z.powi(2)).sqrt();
        let theta = (z / r).acos();
        let phi = y.atan2(x);
        let theta_cos = theta.cos();

        let coords = Coordinates::cartesian(x, y, z);
        assert_relative_eq!(coords.x(), x);
        assert_relative_eq!(coords.y(), y);
        assert_relative_eq!(coords.z(), z);
        assert_relative_eq!(coords.r(), r);
        assert_relative_eq!(coords.theta(), theta);
        assert_relative_eq!(coords.phi(), phi);
        assert_relative_eq!(coords.theta_cos(), theta_cos);
    }

    #[quickcheck]
    fn shcoordinates_cartesian_f32(x: Cartesian, y: Cartesian, z: Cartesian) {
        let x = x.0 as f32;
        let y = y.0 as f32;
        let z = z.0 as f32;
        let r = (x.powi(2) + y.powi(2) + z.powi(2)).sqrt();
        let theta = (z / r).acos();
        let phi = y.atan2(x);
        let theta_cos = theta.cos();

        let coords = Coordinates::cartesian(x, y, z);
        assert_relative_eq!(coords.x(), x);
        assert_relative_eq!(coords.y(), y);
        assert_relative_eq!(coords.z(), z);
        assert_relative_eq!(coords.r(), r);
        assert_relative_eq!(coords.theta(), theta);
        assert_relative_eq!(coords.phi(), phi);
        assert_relative_eq!(coords.theta_cos(), theta_cos);
    }
}