DIFFERENCE _ _ _ _ _ _ _ _ _ _ _ _ operator
The difference operator may be used as either an infix or prefix binary subtraction operator. It is identical to - as a binary operator.
<expression> difference <expression> {difference <expression>}*
<expression> can be a number or any other valid REDUCE expression. Matrix expressions are allowed if they are of the same dimensions.
difference(10,4); 6 15 difference 5 difference 2; 8 a difference b; A - B
The difference operator is left associative, as shown in the second example above.