diff options
Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/nbody.go | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/nbody.go b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/nbody.go new file mode 100644 index 0000000..4eeba44 --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/nbody.go @@ -0,0 +1,180 @@ +//go:build ignore +// +build ignore + +/* +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. + + * Neither the name of "The Computer Language Benchmarks Game" nor the + name of "The Computer Language Shootout Benchmarks" nor the names of + its contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +POSSIBILITY OF SUCH DAMAGE. +*/ + +/* The Computer Language Benchmarks Game + * http://shootout.alioth.debian.org/ + * + * contributed by The Go Authors. + * based on C program by Christoph Bauer + */ + +package main + +import ( + "flag" + "fmt" + "math" +) + +var n = flag.Int("n", 1000, "number of iterations") + +type Body struct { + x, y, z, vx, vy, vz, mass float64 +} + +const ( + solarMass = 4 * math.Pi * math.Pi + daysPerYear = 365.24 +) + +func (b *Body) offsetMomentum(px, py, pz float64) { + b.vx = -px / solarMass + b.vy = -py / solarMass + b.vz = -pz / solarMass +} + +type System []*Body + +func NewSystem(body []Body) System { + n := make(System, len(body)) + for i := 0; i < len(body); i++ { + n[i] = new(Body) // copy to avoid overwriting the inputs + *n[i] = body[i] + } + var px, py, pz float64 + for _, body := range n { + px += body.vx * body.mass + py += body.vy * body.mass + pz += body.vz * body.mass + } + n[0].offsetMomentum(px, py, pz) + return n +} + +func (sys System) energy() float64 { + var e float64 + for i, body := range sys { + e += 0.5 * body.mass * + (body.vx*body.vx + body.vy*body.vy + body.vz*body.vz) + for j := i + 1; j < len(sys); j++ { + body2 := sys[j] + dx := body.x - body2.x + dy := body.y - body2.y + dz := body.z - body2.z + distance := math.Sqrt(dx*dx + dy*dy + dz*dz) + e -= (body.mass * body2.mass) / distance + } + } + return e +} + +func (sys System) advance(dt float64) { + for i, body := range sys { + for j := i + 1; j < len(sys); j++ { + body2 := sys[j] + dx := body.x - body2.x + dy := body.y - body2.y + dz := body.z - body2.z + + dSquared := dx*dx + dy*dy + dz*dz + distance := math.Sqrt(dSquared) + mag := dt / (dSquared * distance) + + body.vx -= dx * body2.mass * mag + body.vy -= dy * body2.mass * mag + body.vz -= dz * body2.mass * mag + + body2.vx += dx * body.mass * mag + body2.vy += dy * body.mass * mag + body2.vz += dz * body.mass * mag + } + } + + for _, body := range sys { + body.x += dt * body.vx + body.y += dt * body.vy + body.z += dt * body.vz + } +} + +var ( + jupiter = Body{ + x: 4.84143144246472090e+00, + y: -1.16032004402742839e+00, + z: -1.03622044471123109e-01, + vx: 1.66007664274403694e-03 * daysPerYear, + vy: 7.69901118419740425e-03 * daysPerYear, + vz: -6.90460016972063023e-05 * daysPerYear, + mass: 9.54791938424326609e-04 * solarMass, + } + saturn = Body{ + x: 8.34336671824457987e+00, + y: 4.12479856412430479e+00, + z: -4.03523417114321381e-01, + vx: -2.76742510726862411e-03 * daysPerYear, + vy: 4.99852801234917238e-03 * daysPerYear, + vz: 2.30417297573763929e-05 * daysPerYear, + mass: 2.85885980666130812e-04 * solarMass, + } + uranus = Body{ + x: 1.28943695621391310e+01, + y: -1.51111514016986312e+01, + z: -2.23307578892655734e-01, + vx: 2.96460137564761618e-03 * daysPerYear, + vy: 2.37847173959480950e-03 * daysPerYear, + vz: -2.96589568540237556e-05 * daysPerYear, + mass: 4.36624404335156298e-05 * solarMass, + } + neptune = Body{ + x: 1.53796971148509165e+01, + y: -2.59193146099879641e+01, + z: 1.79258772950371181e-01, + vx: 2.68067772490389322e-03 * daysPerYear, + vy: 1.62824170038242295e-03 * daysPerYear, + vz: -9.51592254519715870e-05 * daysPerYear, + mass: 5.15138902046611451e-05 * solarMass, + } + sun = Body{ + mass: solarMass, + } +) + +func main() { + flag.Parse() + + system := NewSystem([]Body{sun, jupiter, saturn, uranus, neptune}) + fmt.Printf("%.9f\n", system.energy()) + for i := 0; i < *n; i++ { + system.advance(0.01) + } + fmt.Printf("%.9f\n", system.energy()) +} |