How can I create an array of fixed length?

UPDATE 1: I fixed my resolution issue, but another problem arose.

I'm currently working on a project for examining the Mandelbrot set. My goal is to draw the Mandelbrot set, center the image on a specific location, and then zoom into it. When zooming I receive the following error code:

??? Error using ==> plus

Matrix dimensions must agree.

Error in ==> drawMandelbrot at 20

    z = z.^2 + z0;

When k=32, my z0 matrix goes from being 600x600 to 599x600 preventing me from zooming further because I can't add it to z.^2, which stays a constant 600x600.

_____

function [xctr,yctr] = drawMandelbrot(xmin,xmax,ymin,ymax)

res=599/(xmax-xmin);

x = xmin : 1/res : xmax;

y = ymin : 1/res : ymax;

xctr = (xmin + xmax)/2;

yctr = (ymin + ymax)/2;

Length = length(x);

[X,Y]= meshgrid(x,y);

z0 = X + i*Y;

size(z0)

z = zeros(Length,Length);

c = zeros(Length,Length);

depth = 128;

for k = 1 : depth

      z = z.^2 + z0;

      c(abs(z) < 2) = k;

end

c;

image(c)

axis image

drawnow

colormap(flipud(jet(depth)))

end

______

MAIN

xmin = -2.1;

xmax = .7;

ymin = -1.4;

ymax = 1.4;

[xctr,yctr] = drawMandelbrot(xmin,xmax,ymin,ymax);

xctr_new = -.75;

yctr_new = 0.1;

dx = (xctr_new - xctr)/5;

dy = (yctr_new - yctr)/5;

for j=0:4;

      xmin = xmin + dx;

      xmax = xmax + dx;

      ymin = ymin + dy;

      ymax = ymax + dy;

      [xctr,yctr] = drawMandelbrot(xmin,xmax,ymin,ymax);

end

delx = (xmax - xmin)/100;

dely = (ymax - ymin)/100;

for k=0:99;

      xmin = xmin + .1*k*delx;

      xmax = xmax - .1*k*delx;

      ymin = ymin + .1*k*dely;

      ymax = ymax - .1*k*dely;

      k

      [xctr,yctr] = drawMandelbrot(xmin,xmax,ymin,ymax);

end

_____

Is there a way to prevent 1 row of z0 from being truncated?

Any help is much appreciated.

Answer 1

[Jos (10584)]

Maybe you want to pre-allocate z and c like this:

z = zeros(size(z0)) ;
c = zeros(size(z0)) ;

[John]

Thankyou very much. It worked...did some funky things to the image that i was not expecting , but it worked.

[Akshay Joshi]

Consider the following scenario: I want my vector size to be 5 i.e. if I try to enter 7 elements in a vector, it should throw some error like "Maximum vector size is 5. You cannot insert more than 5 elements in it."

Is there some way to do so??

[Stephen23]

@Akshay Joshi: You will have to either check the indices before allocating, or check the vector size after allocating.