Initial commit

.gitignore

+*.ppm

mandelbrot.c

+/*
+c program:
+--------------------------------
+ 1. draws Mandelbrot set for Fc(z)=z*z +c
+ using Mandelbrot algorithm ( boolean escape time )
+-------------------------------
+2. technique of creating ppm file is  based on the code of Claudio Rocchini
+http://en.wikipedia.org/wiki/Image:Color_complex_plot.jpg
+create 24 bit color graphic file ,  portable pixmap file = PPM
+see http://en.wikipedia.org/wiki/Portable_pixmap
+to see the file use external application ( graphic viewer)
+ */
+#include <stdio.h>
+#include <math.h>
+int main()
+{
+         /* screen ( integer) coordinate */
+       int iX,iY;
+       const int iXmax = 8000;
+       const int iYmax = 8000;
+       /* world ( double) coordinate = parameter plane*/
+       double Cx,Cy;
+       const double CxMin=-2.5;
+       const double CxMax=1.5;
+       const double CyMin=-2.0;
+       const double CyMax=2.0;
+       /* */
+       double PixelWidth=(CxMax-CxMin)/iXmax;
+       double PixelHeight=(CyMax-CyMin)/iYmax;
+       /* color component ( R or G or B) is coded from 0 to 255 */
+       /* it is 24 bit color RGB file */
+       const int MaxColorComponentValue=255;
+       FILE * fp;
+       char *filename="new1.ppm";
+       char *comment="# ";/* comment should start with # */
+       static unsigned char color[3];
+       /* Z=Zx+Zy*i  ;   Z0 = 0 */
+       double Zx, Zy;
+       double Zx2, Zy2; /* Zx2=Zx*Zx;  Zy2=Zy*Zy  */
+       /*  */
+       int Iteration;
+       const int IterationMax=200;
+       /* bail-out value , radius of circle ;  */
+       const double EscapeRadius=2;
+       double ER2=EscapeRadius*EscapeRadius;
+       /*create new file,give it a name and open it in binary mode  */
+       fp= fopen(filename,"wb"); /* b -  binary mode */
+       /*write ASCII header to the file*/
+       fprintf(fp,"P6\n %s\n %d\n %d\n %d\n",comment,iXmax,iYmax,MaxColorComponentValue);
+       /* compute and write image data bytes to the file*/
+       for(iY=0;iY<iYmax;iY++)
+       {
+            Cy=CyMin + iY*PixelHeight;
+            if (fabs(Cy)< PixelHeight/2) Cy=0.0; /* Main antenna */
+            for(iX=0;iX<iXmax;iX++)
+            {
+                       Cx=CxMin + iX*PixelWidth;
+                       /* initial value of orbit = critical point Z= 0 */
+                       Zx=0.0;
+                       Zy=0.0;
+                       Zx2=Zx*Zx;
+                       Zy2=Zy*Zy;
+                       /* */
+                       for (Iteration=0;Iteration<IterationMax && ((Zx2+Zy2)<ER2);Iteration++)
+                       {
+                           Zy=2*Zx*Zy + Cy;
+                           Zx=Zx2-Zy2 +Cx;
+                           Zx2=Zx*Zx;
+                           Zy2=Zy*Zy;
+                       };
+                       /* compute  pixel color (24 bit = 3 bytes) */
+                       if (Iteration==IterationMax)
+                       { /*  interior of Mandelbrot set = black */
+                          color[0]=54;
+                          color[1]=145;
+                          color[2]=230;
+                       }
+                    else
+                       { /* exterior of Mandelbrot set = white */
+                            color[0]=255; /* Red*/
+                            color[1]=255;  /* Green */
+                            color[2]=255;/* Blue */
+                       };
+                       /*write color to the file*/
+                       fwrite(color,1,3,fp);
+               }
+       }
+       fclose(fp);
+       return 0;
+}