From 46afb6bf501f4001c4bdb7bd2f2db7c466f95554 Mon Sep 17 00:00:00 2001
From: Juan Marin Noguera <juan@mnpi.eu>
Date: Tue, 25 Jul 2023 18:22:04 +0200
Subject: Solvned project from 2020

Note that Go didn't have generics back then.
---
 examples/parabolic.go | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 examples/parabolic.go

(limited to 'examples/parabolic.go')

diff --git a/examples/parabolic.go b/examples/parabolic.go
new file mode 100644
index 0000000..f45872b
--- /dev/null
+++ b/examples/parabolic.go
@@ -0,0 +1,110 @@
+// Example visualization of parabolic throw with air friction.
+//
+// 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 addPlot(
+	plot *glot.Plot, name string, arrays [][]float64, idx int, idy int,
+) {
+	if err := plot.AddPointGroup(
+		name,
+		"lines",
+		[][]float64{arrays[idx], arrays[idy]}); err != nil {
+		fmt.Printf("Error adding %v: %w\n", name, err)
+		os.Exit(1)
+	}
+}
+
+func main() {
+	var end mned.Point
+	var err error
+
+	throw := ivp.ParabolicThrow{
+		Height:     300,
+		V0:         [2]float64{100, 0},
+		Mass:       1,
+		Resistance: 0.01,
+		Gravity:    ivp.EARTH_GRAVITY,
+	}
+	problem := throw.ToIVP()
+	solution := mned.CacheSolve(
+		method.Euler(0.01),
+		&problem,
+		mned.LinearInterpolator{},
+		mned.Event{
+			Cross: func(p *mned.Point) float64 {
+				return p.Value[1]
+			},
+			Tolerance: 0.01,
+			Action: func(p *mned.Point) bool {
+				end = *p
+				return false
+			},
+		})
+	solution.StepToEnd()
+	fmt.Printf(
+		"Reached ground after %v s at %v m, with (%v, %v) m/s.\n",
+		end.Time,
+		end.Value[0],
+		end.Value[2],
+		end.Value[3],
+	)
+
+	arrays := solution.PointCoords()
+	byTime, err := glot.NewPlot(2, true, false)
+	if err != nil {
+		fmt.Printf("Creating plot window: %w\n")
+		os.Exit(1)
+	}
+	defer byTime.Close()
+	if err := byTime.SetXLabel("Time (s)"); err != nil {
+		fmt.Printf("Adding X label: %w\n")
+		os.Exit(1)
+	}
+	addPlot(byTime, "X position (m)", arrays, 0, 1)
+	addPlot(byTime, "Y position (m)", arrays, 0, 2)
+	addPlot(byTime, "X speed (m/s)", arrays, 0, 3)
+	addPlot(byTime, "Y speed (m/s)", arrays, 0, 4)
+
+	byTraj, err := glot.NewPlot(2, true, false)
+	if err != nil {
+		fmt.Printf("Creating plot window: %w\n")
+		os.Exit(1)
+	}
+	defer byTraj.Close()
+	if err := byTraj.SetXLabel("X coordinate"); err != nil {
+		fmt.Printf("Adding X label: %w\n")
+		os.Exit(1)
+	}
+	if err := byTraj.SetYLabel("Y coordinate"); err != nil {
+		fmt.Printf("Adding Y label: %w\n")
+		os.Exit(1)
+	}
+	addPlot(byTraj, "Trajectory (m)", arrays, 1, 2)
+	addPlot(byTraj, "Speed trajectory (m/s)", arrays, 3, 4)
+}
-- 
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