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*

* Function

Syntax:

* &rest numbers → product

Arguments and Values:

number—a number .

product—a number .

Description:

Returns the product of numbers, performing any necessary type conversions in the process. If no numbers are supplied, 1 is returned.

Examples:

(\*) → 1 
(\* 3 5) → 15 
(\* 1.0 #c(22 33) 55/98) → #C(12.346938775510203 18.520408163265305)

Exceptional Situations:

Might signal type-error if some argument is not a number . Might signal arithmetic-error.

See Also:

Section 12.1.1 (Numeric Operations), Section 12.1.3 (Rational Computations), Section 12.1.4 (Floating-point Computations), Section 12.1.5 (Complex Computations)

Expanded Reference: *​

Basic multiplication​

* returns the product of its arguments. With no arguments, it returns the multiplicative identity 1.

(*)
=> 1
(* 6)
=> 6
(* 3 5)
=> 15
(* 2 3 4 5)
=> 120

Rational multiplication​

With rational arguments, the result is an exact rational.

(* 1/2 1/3)
=> 1/6
(* 3/4 4/3)
=> 1
(* 2 3/5)
=> 6/5

Floating-point contagion​

If any argument is a float, the result is a float.

(* 2 3.0)
=> 6.0
(* 0.5 10)
=> 5.0
(* 1.0d0 3)
=> 3.0d0

Complex multiplication​

* works with complex numbers following standard complex multiplication rules.

(* #c(0 1) #c(0 1))
=> -1
(* #c(1 1) #c(1 -1))
=> 2
(* #c(2 3) 2)
=> #C(4 6)

Computing factorials​

* is useful with reduce or apply for computing products over sequences.

(reduce #'* '(1 2 3 4 5))
=> 120
(apply #'* (loop for i from 1 to 10 collect i))
=> 3628800