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The Compleat User RPL Encyclopedia


(“Multiply”)

          X Y    X*Y
[[A×B matrix]] [[B×C matrix]]    [[A×C matrix]]     
[[A×B matrix]] [B-element vector]    [A-element vector]     
Keyboard Access (all models): the key (the key below the key, not to be confused with the X letter key on the HP49/50).

Multiply, analytic function. AKA “times”.

Numeric multiplication is commutative (that is, the order of the arguments doesn't matter).

For matrices to be compatible for multiplication, they must have the same inner dimension; that is, an A×B matrix can only be multiplied by a B×C matrix (or a vector with B elements). Matrix multiplication is not commutative. Example:

Although the multiply key looks like the traditional × multiplication symbol, the multiply operator is shown in the display as an asterisk to distinguish it from the letter X. Most other programming languages do this too. Example:  multiplies X times Y, as does .

HP49/50 maximum integer inputs: no limit, but multiplying huge integers takes a long time. For example, multiplying two 1000-digit-long numbers consisting only of 9’s (  ) takes 14 seconds on an HP50g.

BYTES: 2.5