1/*
2 * Copyright (c) 2022-2024 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16import { PI } from "std/math";
17
18// readonly expected : double = -1.3524862408537381;
19class Body  {
20    readonly SOLAR_MASS : double = 4 * PI * PI;
21     x : double ;
22     y : double ;
23     z : double ;
24     vx : double ;
25     vy : double ;
26     vz : double ;
27     mass : double ;
28     public constructor(x : double, y : double, z : double, vx : double, vy : double, vz : double, mass : double) {
29         this.x = x;
30         this.y = y;
31         this.z = z;
32         this.vx = vx;
33         this.vy = vy;
34         this.vz = vz;
35         this.mass = mass;
36     }
37
38     public offsetMomentum(px : double, py : double, pz : double): Body {
39         this.vx = -px / this.SOLAR_MASS;
40         this.vy = -py / this.SOLAR_MASS;
41         this.vz = -pz / this.SOLAR_MASS;
42         return this;
43     }
44}
45
46class NBodySystem  {
47     bodies : Body[] ;
48     public constructor(bodies : Body[]) {
49         this.bodies = bodies;
50         let px : double = 0.0;
51         let py : double = 0.0;
52         let pz : double = 0.0;
53         let size : int = this.bodies.length;
54         for (let i : int = 0; i < size; i++) {
55             let b : Body = this.bodies[i];
56             let m : double = b.mass;
57             px += b.vx * m;
58             py += b.vy * m;
59             pz += b.vz * m;
60         }
61         this.bodies[0].offsetMomentum(px, py, pz);
62     }
63
64     public advance(dt : double): void {
65         let dx : double ;
66         let dy : double ;
67         let dz : double ;
68         let distance : double ;
69         let mag : double ;
70         let size : int = this.bodies.length;
71         for (let i : int = 0; i < size; i++) {
72             let bodyi : Body = this.bodies[i];
73             for (let j : int = i + 1; j < size; j++) {
74                 let bodyj : Body = this.bodies[j];
75                 dx = bodyi.x - bodyj.x;
76                 dy = bodyi.y - bodyj.y;
77                 dz = bodyi.z - bodyj.z;
78                 distance = sqrt(dx * dx + dy * dy + dz * dz);
79                 mag = dt / (distance * distance * distance);
80                 bodyi.vx -= dx * bodyj.mass * mag;
81                 bodyi.vy -= dy * bodyj.mass * mag;
82                 bodyi.vz -= dz * bodyj.mass * mag;
83                 bodyj.vx += dx * bodyi.mass * mag;
84                 bodyj.vy += dy * bodyi.mass * mag;
85                 bodyj.vz += dz * bodyi.mass * mag;
86             }
87         }
88         for (let i : int = 0; i < size; i++) {
89             let body : Body = this.bodies[i];
90             body.x += dt * body.vx;
91             body.y += dt * body.vy;
92             body.z += dt * body.vz;
93         }
94     }
95     public energy(): double {
96         let dx : double ;
97         let dy : double ;
98         let dz : double ;
99         let distance : double ;
100         let e : double = 0.0;
101         let size : int = this.bodies.length;
102         for (let i : int = 0; i < size; i++) {
103             let bodyi : Body = this.bodies[i];
104             e += 0.5 * bodyi.mass * (bodyi.vx * bodyi.vx + bodyi.vy * bodyi.vy + bodyi.vz * bodyi.vz);
105             for (let j : int = i + 1; j < size; j++) {
106                 let bodyj : Body = this.bodies[j];
107                 dx = bodyi.x - bodyj.x;
108                 dy = bodyi.y - bodyj.y;
109                 dz = bodyi.z - bodyj.z;
110                 distance = sqrt(dx * dx + dy * dy + dz * dz);
111                 e -= (bodyi.mass * bodyj.mass) / distance;
112             }
113         }
114         return e;
115     }
116 }
117
118export class AccessNBody  {
119    static readonly SOLAR_MASS : double = 4 * PI * PI;
120    static readonly DAYS_PER_YEAR : double = 365.24;
121    n1 : int = 3;
122    n2 : int = 24;
123
124    static jupiter(): Body {
125        return new Body(4.84143144246472090e+00, -1.16032004402742839e+00, -1.03622044471123109e-01, 1.66007664274403694e-03 * AccessNBody.DAYS_PER_YEAR, 7.69901118419740425e-03 * AccessNBody.DAYS_PER_YEAR, -6.90460016972063023e-05 * AccessNBody.DAYS_PER_YEAR, 9.54791938424326609e-04 * AccessNBody.SOLAR_MASS);
126    }
127    static saturn(): Body {
128        return new Body(8.34336671824457987e+00, 4.12479856412430479e+00, -4.03523417114321381e-01, -2.76742510726862411e-03 * AccessNBody.DAYS_PER_YEAR, 4.99852801234917238e-03 * AccessNBody.DAYS_PER_YEAR, 2.30417297573763929e-05 * AccessNBody.DAYS_PER_YEAR, 2.85885980666130812e-04 * AccessNBody.SOLAR_MASS);
129    }
130    static uranus(): Body {
131        return new Body(1.28943695621391310e+01, -1.51111514016986312e+01, -2.23307578892655734e-01, 2.96460137564761618e-03 * AccessNBody.DAYS_PER_YEAR, 2.37847173959480950e-03 * AccessNBody.DAYS_PER_YEAR, -2.96589568540237556e-05 * AccessNBody.DAYS_PER_YEAR, 4.36624404335156298e-05 * AccessNBody.SOLAR_MASS);
132    }
133    static neptune(): Body {
134        return new Body(1.53796971148509165e+01, -2.59193146099879641e+01, 1.79258772950371181e-01, 2.68067772490389322e-03 * AccessNBody.DAYS_PER_YEAR, 1.62824170038242295e-03 * AccessNBody.DAYS_PER_YEAR, -9.51592254519715870e-05 * AccessNBody.DAYS_PER_YEAR, 5.15138902046611451e-05 * AccessNBody.SOLAR_MASS);
135    }
136    static sun(): Body {
137        return new Body(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, AccessNBody.SOLAR_MASS);
138    }
139    readonly expected : double = -1.3524862408537381;
140    public run(): void {
141        let ret : double = 0;
142        for (let n : int = this.n1; n <= this.n2; n *= 2) {
143            let bodies : NBodySystem = new NBodySystem([AccessNBody.sun(), AccessNBody.jupiter(), AccessNBody.saturn(), AccessNBody.uranus(), AccessNBody.neptune()]);
144            let max : int = n * 100;
145            ret += bodies.energy();
146            for (let i : int = 0; i < max; i++) {
147                bodies.advance(0.01);
148            }
149            ret += bodies.energy();
150        }
151
152        assert ret == this.expected: "Incorrect result";
153    }
154}
155
156function main(): void {
157  let a = new AccessNBody;
158  a.run();
159}
160