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  ANSI Common Lisp   12 Numbers   12.2 Dictionary of Numbers

12.2.32 gcd Function

Syntax:
gcd &rest integers    greatest-common-denominator

Arguments and Values:
integer - an integer.

greatest-common-denominator - a non-negative integer.

Description:
Returns the greatest common divisor of integers. If only one integer is supplied, its absolute value is returned. If no integers are given, gcd returns 0, which is an identity for this operation.

Examples:
 (gcd)  0
 (gcd 60 42)  6
 (gcd 3333 -33 101)  1
 (gcd 3333 -33 1002001)  11
 (gcd 91 -49)  7
 (gcd 63 -42 35)  7
 (gcd 5)  5
 (gcd -4)  4

Exceptional Situations:
Should signal an error of type type-error if any integer is not an integer.

See Also:
lcm

Notes:
For three or more arguments,

 (gcd b c ... z) ==(gcd (gcd a b) c ... z)

Allegro CL Implementation Details:
None.

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