MANDELBROT
Generate an ASCII Portable Pixel Map (PPM) Image of the Mandelbrot Set

MANDELBROT is a FORTRAN77 program which generates an ASCII Portable Pixel Map (PPM) image of the Mandelbrot set.

The Mandelbrot set is a set of points C in the complex plane with the property that the iteration

        z(n+1) = z(n)^2 + c
      

All the points in the Mandelbrot set are known to lie within the circle of radius 2 and center at the origin.

To make a plot of the Mandelbrot set, one starts with a given point C and carries out the iteration for a fixed number of steps. If the iterates never exceed 2 in magnitude, the point C is taken to be a member of the Mandelbrot set.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

MANDELBROT is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

MANDELBROT_OPENMP, a FORTRAN77 program which generates an ASCII Portable Pixel Map (PPM) image of the Mandelbrot fractal set, using OpenMP for parallel execution.

PPMA_IO, a FORTRAN77 library which handles the ASCII Portable Pixel Map (PPM) format.

RANMAP, a FORTRAN90 program which creates a PostScript file of images of iterated affine mappings;

Reference:

1. Alexander Dewdney,
   A computer microscope zooms in for a close look at the most complicated object in mathematics,
   Scientific American,
   Volume 257, Number 8, August 1985, pages 16-24.
2. Heinz-Otto Peitgen, Hartmut Juergens, Dietmar Saupe,
   Chaos and Fractals - New Frontiers in Science,
   Springer, 1992,
   ISBN: 0-387-20229-3,
   LC: Q172.5.C45.P45.

Source Code:

• mandelbrot.f, the source code.
• mandelbrot.sh, commands to compile the source code.

Examples and Tests:

• mandelbrot.ppm, the ASCII PPM file created by the program.
• mandelbrot.png, a PNG version of the image.

List of Routines:

• MAIN is the main program for MANDELBROT.
• GET_UNIT returns a free FORTRAN unit number.
• PPMA_WRITE writes an ASCII portable pixel map file.
• PPMA_WRITE_DATA writes the data of a PPMA file.
• PPMA_WRITE_HEADER writes the header of a PPMA file.

You can go up one level to the FORTRAN77 source codes.