CODEWITHSUNDEEP
matlabmatplotlibplotmandelbrot
Stupid_Intern
Stupid_Intern

Reputation: 3450

How to plot black and white color picture mandelbrot plot

Below code is taken from here.

I am trying to make following change to the code below

If c is not part of the set, plot a white pixel, and if it is part of the set, plot a black pixel.

Use the imshow command to plot your image

%  Parameters:
%    Input, integer M, the number of pixels in the X direction.
%    Input, integer N, the number of pixels in the Y direction.
%    Input, integer COUNT_MAX, the number of iterations.  While 10 or
%    20 is a reasonable value, increasing COUNT_MAX gives a sharper image.
%
    m=601; 
    n=401;
    count_max = 200;

  %Change the range of x's and y's here 
  x_max =   1;
  x_min = - 2;
  y_max =   1;
  y_min = - 1;

%  Create an array of complex sample points in [x_min,x_max] + [y_min,y_max]*i.
%
  I = ( 1 : m );
  J = ( 1 : n );
  X = ( ( I - 1 ) * x_max + ( m - I ) * x_min ) / ( m - 1 );
  Y = ( ( J - 1 ) * y_max + ( n - J ) * y_min ) / ( n - 1 );
  [ Zr, Zi ] = meshgrid ( X, Y );
  C = complex ( Zr, Zi );
%
%  Carry out the iteration.
%
  epsilon = 0.001;

  Z = C;
  ieps = 1 : numel ( C );

  %Iterate through 1 to maximum no. of iterations
  for i = 1 : count_max
    Z(ieps) = Z(ieps) .* Z(ieps) + C(ieps); 
    W(ieps) = exp ( - abs ( Z(ieps) ) );
    ieps = ieps ( find ( epsilon < W(ieps) ) );
  end
%
%  Display the data.
%
  d = log ( abs ( Z ) );
  t = delaunay ( Zr, Zi );
%
%  To see individual pixels, use 'flat' color.
%
 h = trisurf ( t, Zr, Zi, d, 'FaceColor', 'flat', 'EdgeColor', 'flat' );
%
%  h = trisurf ( t, Zr, Zi, d, 'FaceColor', 'interp', 'EdgeColor', 'interp' );

  view ( 2 )
  axis equal
  axis on
  title_string = sprintf ( 'Mandelbrot set, %d x %d pixels, %d iterations', ...
    m, n, count_max );
  title ( title_string )
  xlabel ('Real Axis');
  ylabel ('Imaginary Axis');
%  Terminate.

For 1st point I have no idea what to do.

For completing the 2nd point: when I replace

view(2) to imshow(2) I don't get the image just the title, labels

And if I change:

view(2) to imshow() I get a 3D plot.

Upvotes: 1

Views: 209

Answers (1)

Suever
Suever

Reputation: 65430

nargin simply reports the number of input arguments that were passed to a function. You can use a series of if statements to check what inputs (if any) the user passed and set default values for ones that they did not pass.

It looks like you made it a script instead of a function and hard-coded values for m, n and count_max at the top. In this scenario, the nargin statements don't matter. However, I would change it back to a function.

function mandelbrot ( m, n, count_max )
    %// If no input were provided use m = 101
    if ( nargin == 0 )
        m = 101;
    end

    %// If the second input wasn't provided, set it equal to m
    if ( nargin <= 1 )
        n = m;
    end

    %// If the third input wasn't provided, set count_max = 20
    if ( nargin <= 2 )
        count_max = 20;
    end

    %// Other stuff here
end

Then you can call it with the parameters you want

mandelbrot(601, 401, 200)

Upvotes: 1

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