How can I create an array of fixed length?

Question

John 2014-3-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/121976-how-can-i-create-an-array-of-fixed-length

编辑： Stephen23 2017-9-9

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.

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Answer 1

Jos (10584) 2014-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/121976-how-can-i-create-an-array-of-fixed-length#answer_128904

在 MATLAB Online 中打开

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

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

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Akshay Joshi 2017-9-9

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 2017-9-9

编辑：Stephen23 2017-9-9

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

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How can I create an array of fixed length?

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