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

C/C++ Source or Header | 1996-02-19 | 5.4 KB | 161 lines

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

//+ Program TCHEBY.CPP - November 13, 1994                                  +

//+                                                                         +

//+ By Fausto Arinos de Almeida Barbuto, Rio de Janeiro, RJ, BRAZIL         +

//+ E-mails: [e-mail]  and  [e-mail]    +

//+                                                                         +

//+ Repeated iterations over the Tschebysheff function over the real domain.+

//+ Based on Pseudocode 15.1 (see REFERENCE below)                          +

//+ Press ESC at any time to fade the screen out and quit.                  +

//+                                                                         +

//+ REFERENCE: Pickover, Clifford A. "Computers, Pattern, Chaos and Beauty" +

//+            1990, St.-Martin's Press, pp. 293.                           +

//+                                                                         +

//+ Uses SVGA256.BGI by Jordan Powell Hargrave and fade-out routine by      +

//+ Michael E. Sargent and Quintessential Sophistry.                        +

//+                                                                         +

//+ Version for spanky.triumf.ca (142.90.112.1), Vancouver, B.C. Canada.    +

//+*************************************************************************+



#include <graphics.h>

#include <stdio.h>

#include <dos.h>

#include <conio.h>

#include <math.h>

#include "svga256.h"



int Video; /* Global variable */



double Chebyshev(int, double);

void fade(void);



int huge DetectSVGA256()

{

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

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

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

  printf(" 2 - 640x480x256 (suggested when available)\n");

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

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

  scanf("%d",&Video);

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

  return Video;

}



void main()

{

      double xmin=-1.0, xmax=1.0, ymin=-1.0, ymax=1.0;

      double xold, yold, r, deltap, deltaq, p, q, x, y, T1, T2, h;

      unsigned int maxiter;

      register int k, np, nq;

      int npix, npiy, order, initcolour, graphdriver=DETECT, graphmode;

//

      clrscr();

      printf("\n Program CHEBY.C - By Fausto A. A. Barbuto, November 1994");

      printf("\n\n WARNING: Some combinations of high 'order', 'h' and");

      printf(" 'maxiter' may cause\n          overflow before the end");

      printf(" of the execution.");

      printf("\n\n Select the order of the polynomial (3 <= order <= 20):");

      printf("\n\n> ");

      scanf("%d",&order);

      if ((order < 3) || (order > 20)) order = 10;

      printf("\n Select a step 'h', 0.0 < h < 1.0 (suggested: 0.1):\n\n> ");

      scanf("%lf",&h);

      printf("\n\n Select the maximum number of iterations");

      printf("\n (Suggestion: start with 20, then increase):\n\n> ");

      scanf("%u",&maxiter);

      clrscr();

      printf("\n Choose a colour scheme:\n\n    'Tropical'    : Enter 30\n");

      printf("    Shades of gray: Enter 16\n    Your own      : ");

      printf("Enter ???\n\n> ");

      scanf("%d",&initcolour);



      installuserdriver("Svga256",DetectSVGA256);

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



      cleardevice();



      if (Video == 0) {npix=320;  npiy=200;}

      if (Video == 1) {npix=640;  npiy=400;}

      if (Video == 2) {npix=640;  npiy=480;}

      if (Video == 3) {npix=800;  npiy=600;}

      if (Video == 4) {npix=1024; npiy=768;}



      deltap = (xmax-xmin)/(double)(npix-1);

      deltaq = (ymax-ymin)/(double)(npiy-1);



      for (np=0; np<=npix-1; np++) {

    p = xmin + (double)np*deltap;

    for (nq=0; nq<=npiy-1; nq++) {

      q = ymin + (double)nq*deltaq;

      x = p; y = q;

      k = 0;

      do {

        xold = x; yold = y;

        T1 = Chebyshev(order,yold);

        x = x - h*sin(T1);

        T2 = Chebyshev(order,xold);

        y = y + h*sin(T2);

        r = sqrt(T1*T1 + T2*T2);

        k++;



        if (r >= maxiter) {

          putpixel(np,nq,(initcolour+k));

        }



        if (k == maxiter) {

          putpixel(np,nq,1);

        }



      } while (r<=maxiter && k<=maxiter);

    }

    if (kbhit()) break;

      }

      getch();

      fade();

      closegraph();

}



double Chebyshev(int nn, double xx)

{

   double z3, Tc[20], T;

   register int ii;



     z3 = xx*xx*xx;

     Tc[2] = 2.0*xx*xx - 1.0;

     Tc[3] = 4.0*z3 - 3.0*xx;

     for (ii=3;ii<=nn;ii++) {

       Tc[ii+1] = 2.0*xx*Tc[ii] - Tc[ii-1];

       T = Tc[ii+1];

     }

     return T;

}

//+======================================================================+

// Fade-out routine by Michael E. Sargent & The Quintessential Sophistry +

//=======================================================================+

#pragma warn -eff

void fade(void)

{

   int a, b, p1, p2, p3;



   for (a=0; a<64; a++)

   {

      for (b=0; b<256; b++)

      {

     outp(0x3C7, b);

     p1 = inp(0x3C9);

     p2 = inp(0x3C9);

     p3 = inp(0x3C9);

     outp (0x3C8, b);

     if (p1 > 0) outp(0x3C9, p1 - 1);

        else outp(0x3C9, 0);

     if (p2 > 0) outp(0x3C9, p2 - 1);

        else outp(0x3C9, 0);

     if (p3 > 0) outp(0x3C9, p3 - 1);

        else outp(0x3C9, 0);

      }

   delay(75);

   }

}

#pragma warn +eff