I'm having trouble making the Mandelbrot set

kellen

Hi, I'm new to programming and I'm trying to make the Mandelbrot set. I am trying to make a nestled loop for the x and y values of the window (corresponding to a and b for the complex number input a + bi ). I want it to create a function for each one that performs the function z^2 + c and changes the color of the point it draws based on how long it took z to get to infinity (16).

int maxIterations = 50;
float infinity = 16;

void setup(){
size(720,720);
background(0);

  for(int x = 0; x < width; x++){
    for(int y = 0; y<height; y++){

float a = (x-360)/180;
float b = (y-360)/180;   
float c = a + b*sqrt(-1);                 
cSet( c , 0 , 0 , x ,y);            
    }
  }
}

void cSet(float c, float z, int iterations, int x, int y){ 

if(iterations < maxIterations && z < infinity){  
cSet( c , pow(z,2) + c , iterations + 1 , x , y);    
  }

if(z > infinity){
stroke(iterations*5);
point(x,y); 
  }

}

TfGuy44

I just happen to have this handy.

float pxi=-2;
float pyi =-2;// -0.5;

float pxa = 2;
float pya =2;


void setup() {
  size(800,800);

//  pxi = -( width / (height/-pyi+pya) );
//  pxa = -pxi;

  float dx = 1;
//  pxi+=dx;
//  pxa+=dx;

  colorMode(HSB, 255);
}

void draw() {
  loadPixels();
  int max = 50;
  for ( int x = 0; x < width; x++) {
    for ( int y = 0; y < height; y++) {
      float a = map( x, 0, width, pxi, pxa);
      float b = map( y, 0, height, pyi, pya);
      float ca = a;
      float cb = b;

      int n = 0;
      //int z = 0;
      while ( n < max ) {
        float aa = a * a - b * b;
        float bb = 2 * a * b;

        if ( abs( a + b ) > 16) {
          break;
        }

        a = aa + ca;
        b = bb + cb;

        n++;
      }


      float hhue = (128 + map(n, 0, max, 0, 255))%255;
      float bright = 255;
      if ( n == max ) {
        bright = 0;
      }

      pixels[y*width+x] = color(hhue, 255, bright);
    }
  }
  updatePixels();
  noLoop();
  //saveFrame();
  //exit();
}

void mousePressed() {
  if ( mouseButton == LEFT) {
    pxi = map(mouseX, 0, width, pxi, pxa);
    pyi = map(mouseY, 0, height, pyi, pya);
    loop();
  }
  if ( mouseButton == RIGHT) {
    pxa = map(mouseX, 0, width, pxi, pxa);
    pya = map(mouseY, 0, height, pyi, pya);
    loop();
  }
}

kellen

That works but I'm more looking to figure out why my code doesn't work. Right now its just a black canvas.

GoToLoop

http://Studio.ProcessingTogether.com/sp/pad/export/ro.96P5CDnO6mAXt

kellen

Okay so I think the problem has to do with processing not being able to use complex numbers. Anyone know how to fix this?

GoToLoop

Java Mode: https://Forum.Processing.org/two/discussions/tagged/complex

Python Mode:

1. http://www.Jython.org/docs/library/stdtypes.html#numeric-types-int-float-long-complex
2. http://www.Jython.org/docs/library/cmath.html

koogs

float c = a + b * sqrt(-1);

ha ha ha

koogs

you have to treat the two parts of the complex number separately. hold them in a pvector or two separate variables.

sqrt(-1) is undefined.