計算機シミュレーションの時間。
ウサギとキツネについての連立一次微分方程式を適当に解く。
import java.io.*; public class Report1{ public static void main(String[] args) throws IOException{ // rabbit and fox double r0 = 3; double f0 = 1; double rt,rtt,ft,ftt; double br = 1; double df = 1; double a = 0.2; double b = 0.02; // time double t; double t0 = 0.0; double tt = 25.0; double dt = 0.01; // init rt = ( 1.0 + ( br - a * f0 ) * dt ) * r0; ft = ( 1.0 + ( b * r0 - df ) * dt ) * f0; File file = new File("test.csv"); PrintWriter pw = new PrintWriter(new FileWriter(file)); //0 pw.println("0,"+rt+","+ft); for(t = t0; t < tt; t += dt){ double tr = rt; rtt = ( 1.0 + ( br - a * ft ) * dt ) * rt; ftt = ( 1.0 + ( b * rt - df ) * dt ) * ft; pw.println(t+","+rtt+","+ftt); rt = rtt; ft = ftt; } pw.close(); } }