The
slide rule, also known colloquially in the United States as a
slipstick, is a mechanical
analog computer. The slide rule is used primarily for
multiplication and
division, and also for functions such as
roots,
logarithms and
trigonometry, but is not normally used for
addition or
subtraction. Though similar in name and appearance to a standard
ruler, the slide rule is not ordinarily used for measuring length or drawing straight lines.