code/mandelbrot/mandelbrot.c

#include <stdio.h>

#define BAIL_OUT 16
#define MAX_ITER 100

#define WIDTH 800
#define HEIGHT 800

double map(int value, int min, int max, int map_min, int map_max)
{
	double R = (double) (map_max - map_min) / (double) (max - min);
	double y = map_min + (value * R) + R;
	return y;
}

void mandelbrot(double *field, int w, int h, int bail_out, int max_iter)
{
	double xPrime, yPrime, real, imaginary, realPrime,
	    imaginaryPrime,x2, y2;
	int bailed = 0, x, y, k;
	for (x = 0; x < w; x++) {
		for (y = 0; y < h; y++) {
			xPrime = map(x, 0, w, -2, 2);
			yPrime = map(y, 0, h, -2, 2);
            x2 = xPrime;
            y2 = yPrime;

            // iterate a^2 - b^2 + 2ab
			for (k = 0; k < max_iter; k++) {
                bailed = 0;
                // a^2 - b^2
				real = xPrime * xPrime - yPrime * yPrime;
                // 2ab
				imaginary = 2 * xPrime * yPrime;
                
                // real + c
				xPrime = real + x2;
                // imaginary + c
				yPrime = imaginary + y2;

				if ((xPrime * xPrime + yPrime * yPrime) >
				    bail_out) {
					break;
				}
			}

			if (k == max_iter) {
				field[x * h + y] = 0;
			} else {
                field[x * h + y] = k;
			}
		}
	}
}

int main(int argc, char **argv)
{

	double pix_field[WIDTH][HEIGHT];

	mandelbrot((double *) pix_field, WIDTH, HEIGHT, BAIL_OUT, MAX_ITER);

    for (int i=0; i< WIDTH; i++)
    {
        for (int j=0; j<HEIGHT; j++)
        {
            printf("[%.2lf]", pix_field[i][j]);
        }

        printf("\n");
        
    }

    return (0);

}