what does ~ do in this code?

I was given a couple lines of code for part of a project and im trying to figure out how it does what it does.

[~,pivot]=rref(A) 
B=A(:,pivot)

The code is given a matrix A, and matrix B is a matrix of just the pivot columns of A.

my main confusion is around the first line, with the ~ operator. In most cases i've seen, ~ indicates "not", but here it seems to be doing something different

Answer 1

[Star Strider]

The tilde ~ tells rref not to return the first output.

See: MATLAB Operators and Special Characters for details on it and other special characters.