#include <math.h> double cos(double x);
cos
computes the trigonometric cosine of the value x
. The
cos
function expects a value of x
expressed in radians.
Because the cosine function is periodic, only the value of x mod 2 pi is used
to compute the cosine. If x
is very large, only a limited precision is
left to represent x mod 2 pi. Thus, an error message is written for very large
negative or positive arguments (see DIAGNOSTICS below).
cos
returns the value of the cosine of the argument x
,
provided that this value is defined and computable. The return value is of type
double
.
x
> 6.7465e9), the function returns 0.0. In
this case, the message "total loss of significance" is also written to
stderr
(the standard error file).
If an error occurs in cos
, the _matherr
routine is called. You
can supply your own version of _matherr
to suppress the diagnostic
message or modify the value returned.
cos
:
#include <stdio.h> #include <lcmath.h> main() { double y; /* The constant M_PI is declared in the */ /* header file <lcmath.h>. 60 degrees */ /* is pi/3 radians. */ y = cos(M_PI/3); printf("cos(%f) = %fn",M_PI,y); }
sin
, tan
, _matherr
Copyright (c) 1998 SAS Institute Inc. Cary, NC, USA. All rights reserved.