Expressions are the basic building block of statements in Octave. An expression evaluates to a value which you can print, test, store in a variable pass to a function, or assign a new value to a variable with an assignment operator.
An expression can serve as a statement on its own. Most other kinds of statements contain one or more expressions which specify data to be operated on. As in other languages expressions in Octave include variables array references, constants, and function calls, as well as combinations of these with various operators.