pcolor returns error second time around

I ran this code for julia sets with x=-2:0005:2, y=-2:0.005:2 and it worked perfectly. I now changed the values of x and y. and it gives the error message below.

c=-0.835 - 1i*0.232;
x=-0.2:0.005:0.2;
y=-0.2:0.005:0.2;
[X,Y]=meshgrid(x,y);
z=(X + Y*1i);
n_max=256;
b=10000; %blowup parameter. stop an iteration when |z|==b.
n_matrix=zeros(800,800);
for n = 1:n_max
    f_z = z.^2 + c;
    z = f_z ;
   if abs(z)>10000  
      n_matrix(n)=n;
         if (z.^2+c)^n_max<10000
       n_matrix(n)=n;

     end       
     end
  end
  colormap prism(256)
  pcolor(n);
  shading flat;
  axis('square','equal','off')

    Error using pcolor (line 54)
Color data input must be a matrix.

Error in julia (line 24) pcolor(n);

Answer 1

[Image Analyst]

Use imagesc(n_matrix) instead of pcolor(n). You have some other problems though.

[Ejike]

please what are the other problems

[Image Analyst]

Well, did it run perfectly and do what you want after you replaced pcolor with imagesc?

Answer 2

[Walter Roberson]

colormap prism(256)

should be

colormap(prism(256))