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Date: Tue, 19 Apr 1994 09:27:00 BSC
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From: BJ06@C53000.PETROBRAS.ANRJ.BR
Subject: DUFFING.CPP (C++ 3.1 source code)
Lines: 75
 
---Program DUFFING.CPP---Begin---CUT HERE--------------------------------
//
//+---------------------------------------------------------------------+
//+ Program DUFFING.CPP                                                 +
//+ By Ramiro Perez {RPEREZ@UTPVM1.BITNET}, (Panama)                    +
//+ and Fausto A. A. Barbuto {BJ06@C53000.PETROBRAS.ANRJ.BR}, (Brazil). +
//+ C++ 3.1 programme's creator: Fausto A. A. Barbuto, April 18, 1994.  +
//+ After a TURBO BASIC program by Ramiro Perez.                        +
//+                                                                     +
//+ Plots Duffing's oscillator with shaded, colourful spheres.          +
//+                                                                     +
//+ VGA 16 colours version.                                             +
//+ Press any key to stop and PAUSE to freeze the execution.            +
//+---------------------------------------------------------------------+
//
#include <graphics.h>
#include <conio.h>
#include <stdio.h>
#include <dos.h>
#include <math.h>
 
void Draw (double, double, int);
 
void main()
{
    int k, k1;
    int ipal[14] = {8,1,9,25,11,43,31,32,4,52,36,38,54,62};
    double a, cl, t, x, y, x1, y1, pi=3.141592653589793, twopi;
    int graphdriver=DETECT, graphmode;
 
    initgraph(&graphdriver,&graphmode,"C:\\BORLANDC\\BGI");
    cleardevice();
 
    x = 1.0;
    y = 0.0;
    t = 0.0;
    a = 0.3;
    twopi = 2.0*pi;
    for (k=0;k<=13;k++) setpalette(k,ipal[k]);
 
    do {
      k1++;
      x1 = x + y/twopi;
      y1 = y + (-(x*x*x) + x -0.25*y + a*cos(t))/twopi;
      t  = 0.01*(k1 % 628);
      x = x1;
      y = y1;
      if (t > pi) cl = 0;
      else cl = 7;
      Draw(x,y,cl);
      delay(9); // Change the time delay to see the plot slower/faster
    } while (!kbhit());
    getch();
    closegraph();
}
 
void Draw (double x, double y, int cl)
{
    double i1, j1, c;
    int i, k, colour;
 
    i1 = 150.0*x + 320.0;
    j1 = -88.0*y + 240.0;
    k = 7;
 
    for (i=1;i<=7;i++) {
      c = 0.09*i;
      colour = (i + cl);
      setcolor(colour);
      setfillstyle(SOLID_FILL,k);
      circle ((int)(i1+c),(int)(j1+c),k);
      k--;
    }
    return;
}
---Program DUFFING.CPP---End---CUT HERE---------------------------------