Does MATLAB copy large input parameters or does it operate on pointers?

X is a large Array of matrices which is passed to a function f(X). Does MATLAB copy this Matrix or does the function f(X) read the original Matrix by means of pointers?

Answer 1

[Adam]

Matlab takes a copy of a matrix only when you make a change to that matrix, so even though it does not use pass by reference (except for handle-derived classes) it will not take a copy of an array if you pass it to another function and use it for read-only purposes. The copy will happen when you make a change to the array in your function. i.e. essentially it uses copy-on-write semantics.