Nyquist / XLISP 2.0 -
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acos
Type: |
- |
Lisp function (closure) |
Source: |
- |
|
Syntax
- (acos flonum)
- flonum - an integer or floating point expression
returns - the arc-cosine of the number
Note: the 'acos' function is not implemented in Nyquist. Here
is a Lisp implementation of 'acos', using the atan
function:
(defun acos (x)
(cond ((not (numberp x)) (error "bad argument type" x))
((= x 1) 0.0)
((= x -1) pi)
((< -1 x 1) (+ (atan (/ (- x) (sqrt (1+ (* x (- (float x))))))) (/ pi 2.0)))
(t (error "argument out of range" x))))
Description
The 'acos' function returns the arc-cosine of an integer or
floating point expression. The result is a floating point
number in radians. If the argument is less than -1
or greater than +1, the arc-cosine is a complex
number. Complex numbers are not available in XLISP. In
this case the 'acos' function signals an 'argument out of range'
error.
Examples
(acos 0.0) => 1.5708
(acos 1.0) => 0.0
(acos -1.0) => 3.14159
See also:
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Nyquist / XLISP 2.0 -
Contents |
Tutorials |
Examples |
Reference