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  ANSI Common Lisp   12 Numbers   12.2 Dictionary of Numbers

12.2.18 zerop Function

Syntax:
zerop number    generalized-boolean

Pronunciation:
[ 'zê(')rô(')pê ]

Arguments and Values:
number - a number.

generalized-boolean - a generalized boolean.

Description:
Returns true if number is zero (integer, float, or complex); otherwise, returns false.

Regardless of whether an implementation provides distinct representations for positive and negative floating-point zeros, (zerop -0.0) always returns true.

Examples:
 (zerop 0)  true
 (zerop 1)  false
 (zerop -0.0)  true
 (zerop 0/100)  true
 (zerop #c(0 0.0))  true

Exceptional Situations:
Should signal an error of type type-error if number is not a number.

Notes:
 (zerop number) ==(= number 0)

Allegro CL Implementation Details:
None.

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