MATLAB Answers

0

How to make empty array of specific size?

Asked by Zeynab Mousavikhamene on 14 Oct 2019
Latest activity Answered by Walter Roberson
on 14 Oct 2019
a=ClassName.empty(2,2)
but I got this error:
Undefined variable "ClassName" or class "ClassName.empty".

  2 Comments

You would have to substitute the name of the class for ClassName
@Walter Roberson I changed to a.empty(2,2). But now a=0 and isempty(a)=0. Why? It should be ''empty'', not zero

Sign in to comment.

Tags

2 Answers

Answer by Steven Lord
on 14 Oct 2019

Replace ClassName with the name of the class for which you want to create the empty array.
But in order to use the empty method, the size of the array you want to create must be 0 in at least one of its dimensions. You can't, for example, have a 2-by-2 empty array. If you want to make a double 2-by-2 array, use zeros, ones, rand, eye, etc.
x = zeros(2); % 2-by-2 double array filled with 0's
y = ones(2, 'single'); % 2-by-2 single array filled with 1's
z = int8.empty(2, 2, 0) % 2-by-2-by-0 int8 array

  2 Comments

@ Steven Lord Thanks but as I said in the question, for some reason I dont want to create with numbers like zero or one and it seems matlab does not have that capability.
If the array has at least one element, those elements must have a value. Let's say you created your "empty" 2-by-2 matrix a. What specifically do you want the value of q to be after running the following line of code?
q = a(1, 1);

Sign in to comment.


Answer by Walter Roberson
on 14 Oct 2019

https://www.mathworks.com/matlabcentral/fileexchange/31362-uninit-create-an-uninitialized-variable-like-zeros-but-faster

  0 Comments

Sign in to comment.