Rat's Nest 1/ratsnest1.iso/prgmming/c/lorenz.cpp

C/C++ Source or Header | 1996-02-19 | 4.8 KB | 154 lines

//

//+---------------------------------------------------------------------+

//+ Program LORENZ.CPP                                                  +

//+ By Ramiro Perez {[e-mail]}, (Panama)                    +

//+ and Fausto A. A. Barbuto {[e-mail]}, (Brazil). +

//+ C++ 3.1 programme's creator: Fausto A. A. Barbuto, April 14, 1994.  +

//+ After a TURBO BASIC program by Ramiro Perez.                        +

//+                                                                     +

//+ Plots Lorenz attractors with shaded, colourful spheres.             +

//+                                                                     +

//+ SVGA 256 colours version. Needs SVGA256.BGI and SVGA256.H.          +

//+ We suggest to change the start-up values of the arrays xa, ya, and  +

//+ za to witness how the attractor's shape change.                     +

//+ Press any key to stop and PAUSE to freeze the execution.            +

//+ Authorized version for spanky.triumf.ca site.                       +

//+---------------------------------------------------------------------+

//

#include <graphics.h>

#include <conio.h>

#include <stdio.h>

#include <dos.h>

#include "svga256.h"



void Draw (double, double, int);

int Vid;  //Global variable



int huge DetectSVGA256()

{

  printf("\nWhich video mode would you like to use? \n\n");

  printf(" 0 - 320x200x256\n");

  printf(" 1 - 640x400x256\n");

  printf(" 2 - 640x480x256\n");

  printf(" 3 - 800x600x256\n");

  printf(" 4 - 1024x768x256\n\n> ");

  scanf("%d",&Vid);

  if((Vid<0) || (Vid)>4) Vid = 2;

  return Vid;

}



void main()

{

    int c, b, a, l, Iopt;

    double c1, cl, dt, xa[2], ya[2], za[2], x, y, z, x1, y1, z1, xd, yd;

    int graphdriver=DETECT, graphmode;



    clrscr();

    printf("\n                           Program LORENZ.CPP\n\n");

    printf("\n    Select an option:\n\n");

    printf("\n                0: Ramiro's default start-up values;\n");

    printf("\n                1: Enter your own start-up values;\n\n>> ");

    scanf("%d",&Iopt);

    if ((Iopt > 1) || (Iopt < 0)) Iopt = 0;

    clrscr();



    if (Iopt == 1) {

      printf("\n Enter initial value for xa[0] (-99: default is used)\n> ");

      scanf("%lf",&xa[0]);

      if (xa[0] == -99.0) xa[0] = 3.051522;

      printf("\n Enter initial value for xa[1] (-99: default is used)\n> ");

      scanf("%lf",&xa[1]);

      if (xa[1] == -99.0) xa[1] = 3.051522;

      printf("\n Enter initial value for ya[0] (-99: default is used)\n> ");

      scanf("%lf",&ya[0]);

      if (ya[0] == -99.0) ya[0] = 1.592542;

      printf("\n Enter initial value for ya[1] (-99: default is used)\n> ");

      scanf("%lf",&ya[1]);

      if (ya[1] == -99.0) ya[1] = 1.582542;

      printf("\n Enter initial value for za[0] (-99: default is used)\n> ");

      scanf("%lf",&za[0]);

      if (za[0] == -99.0) za[0] = 15.62388;

      printf("\n Enter initial value for za[1] (-99: default is used)\n> ");

      scanf("%lf",&za[1]);

      if (za[1] == -99.0) za[1] = 15.62388;

      clrscr();

    }



    installuserdriver("Svga256",DetectSVGA256);

    initgraph(&graphdriver,&graphmode,"C:\\BORLANDC\\BGI");

    cleardevice();



    c1 = 0.292893;

    dt = 0.02;

    a  = 5;

    b  = 15;

    c  = 1;

//

//  Default start-up values for xa, ya and za.

//

    if (Iopt == 0) {

      xa[0] = 3.051522;

      ya[0] = 1.592542;

      za[0] = 15.62388;

      xa[1] = xa[0];

      ya[1] = 1.582542;

      za[1] = za[0];

    }



    do {

      for (l=0;l<=1;l++) {

    x = xa[l];

    y = ya[l];

    z = za[l];

    x1 = x - a*x*dt + a*y*dt;

    y1 = y + b*x*dt - y*dt - z*x*dt;

    z1 = z - c*z*dt + x*y*dt;

    x = x1;

    y = y1;

    z = z1;

    xd = y - x*c1;

    yd = z + x*c1;

    if (l==1) {

      cl = 0;

      Draw(xd,yd,cl);

    }

    else {

      cl = 7;

      Draw(xd,yd,cl);

    }

    delay(4);  //Change the time delay to see it slower/faster;

    xa[l] = x;

    ya[l] = y;

    za[l] = z;

      }

    } while (!kbhit());

    getch();

    closegraph();

}



void Draw (double xd, double yd, int cl)

{

    double i1, j1, c, c1, c2, d1, d2;

    int i, k, colour;



    if (Vid == 0) { c1 =  9.7; c2 = 160.0; d1 =  4.6; d2 = 175.0; k=4;}

    if (Vid == 1) { c1 = 19.3; c2 = 325.0; d1 =  9.2; d2 = 345.0; k=7;}

    if (Vid == 2) { c1 = 19.3; c2 = 320.0; d1 = 11.0; d2 = 392.0; k=7;}

    if (Vid == 3) { c1 = 30.0; c2 = 400.0; d1 = 17.1; d2 = 550.0; k=9;}

    if (Vid == 4) { c1 = 38.4; c2 = 500.0; d1 = 21.9; d2 = 675.0; k=12;}



    i1 = c1*xd + c2;

    j1= -d1*yd + d2;



    for (i=1;i<=7;i++) {

      c = 0.09*i;

      colour = (i + cl) + 33;

      setcolor(colour);

      setfillstyle(SOLID_FILL,k);

      circle ((int)(i1+c),(int)(j1+c),k);

      k--;

    }

    return;

}