Is there any ways that I can preallocate the unknown sized array or matirx?

I Just want to know if I can make a preallocate array.

Please also explain me how much difference is there between the preallocated program and the unpreallocated one.. (for a small program).

Answer 1

[Ameer Hamza]

Pre-allocation will make a huge difference if your array size is very large. See a comparison here: https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html. That being said, for a small array size, you might not notice a considerable difference. However, as a general principle, pre-allocation is a good idea. If the array size is unknown initially, you can do incremental growth of the array. This FEX package by John: https://www.mathworks.com/matlabcentral/fileexchange/8334-incremental-growth-of-an-array-revisited has an excellent implementation of incremental pre-allocation. You can directly use it in your project.

[Wai Han]

Thank you. The code explains to me the significant ideas behind the preallocation and how to use it.