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// Example visualization of the Arenstorf orbit.
//
// Copyright (C) 2020 Juan Marín Noguera
//
// This file is part of Solvned.
//
// Solvned is free software: you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version.
//
// Solvned is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
// details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Solvned. If not, see <https://www.gnu.org/licenses/>.
package main
import (
"fmt"
"github.com/Arafatk/glot"
"github.com/JwanMan/mned"
"github.com/JwanMan/mned/ivp"
"github.com/JwanMan/mned/method"
"os"
)
func main() {
var backed bool = false
problem := ivp.ArenstorfOrbit()
solution := mned.CacheSolve(
method.RKFehlberg(0.01, 0.01, 1e-7, 0.1),
&problem,
mned.HermiteForIVP(&problem),
mned.Event{
Cross: func(p *mned.Point) float64 {
return p.Value[1]
},
Tolerance: 0.01,
Action: func(p *mned.Point) bool {
if p.Value[0] < 0 {
backed = true
}
return true
},
},
mned.Event{
Cross: func(p *mned.Point) float64 {
return p.Value[1]
},
Tolerance: 0.01,
Action: func(p *mned.Point) bool {
return p.Value[0] <= 0.9 || !backed
},
},
)
solution.StepToEnd()
coords := solution.PointCoords()
fmt.Printf("Took %v steps.\n", len(coords[0]))
plot, err := glot.NewPlot(2, true, false)
if err != nil {
fmt.Printf("Couldn't create plot: %v\n", err)
os.Exit(1)
}
if err := plot.AddPointGroup("Orbit", "lines", [][]float64{
coords[1], coords[2],
}); err != nil {
fmt.Printf("Couldn't draw the points: %v\n", err)
os.Exit(1)
}
}
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