subset based on a conditin in matlab

To subset or filter an array based on a condition in MATLAB, you can use logical indexing. This involves creating an index of true and false values, indicating which elements of the array satisfy the condition. You can then use this index to subset the array.

Here is an example that filters an array of numbers to only include even numbers:

main.m
% create array of numbers
a = [1 2 3 4 5 6 7 8 9 10];

% create logical index of even numbers
even_idx = mod(a,2) == 0;

% use logical index to subset array
even_nums = a(even_idx);
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In this example, the mod function is used to compute the remainder of each element of a when divided by 2. The result is a new array of the same size as a, with 1's in positions where the original element was even, and 0's where it was odd. The == operator is used to create a logical array with 1's in the same positions as the even elements of a. This is the index used to subset the array, resulting in a new array containing only the even numbers.

You can adapt this approach to any condition you want to check for, by creating the appropriate logical index.