How to create an array which changes with each iteration of a loop?

How to create an array which changes with each iteration of a for loop? for example;

polyX(i)=horzcat(X2(i),X1(i+1),V(i+1));

polyX is an array.

Answer 1

[Star Strider]

It is not certain what you want to do. We don’t know what scalars or arrays you’re concatenating, so I would create ‘polyX’ as a cell array, since cell arrays are much more tolerant of changing dimensions than matrices:

polyX{i} = horzcat(X2(i),X1(i+1),V(i+1));

Note the curly braces ‘{}’ denoting that ‘polyX’ is now a cell array. See the documentation on Cell Arrays for details.

[KalMandy]

Thank you Star. is it possible that I can use a similar cell array polyY{i} and write,

area(i)=polyarea( polyX{i}, polyY{i})

[Star Strider]

My pleasure.

That will probably work. (I caution ‘probably’ because I don’t know what ‘polyX’ and ‘polyY’ are.)

Also, please re-name your ‘area’ variable to something else, since area is a function (similar to patch) that fills a plotted area with a colour. (This is known as ‘overshadowing’ and will cause serious problems if you need to use the area function later in your code, and you may want to use it.) Instead, name it ‘p_area’ or something that describes what it is, and also has a name different than MATLAB built-in functions.

[KalMandy]

Thank you very much, Your explanations are very easy to follow!

[Star Strider]

As always, my pleasure!