cos, cosf, cosl - cppreference.com (original) (raw)

Defined in header <math.h>
float cosf( float arg ); (1) (since C99)
double cos( double arg ); (2)
long double cosl( long double arg ); (3) (since C99)
_Decimal32 cosd32( _Decimal32 arg ); (4) (since C23)
_Decimal64 cosd64( _Decimal64 arg ); (5) (since C23)
_Decimal128 cosd128( _Decimal128 arg ); (6) (since C23)
Defined in header <tgmath.h>
#define cos( arg ) (7) (since C99)

1-6) Computes the cosine of arg (measured in radians).

  1. Type-generic macro: If the argument has type long double, (3) (cosl) is called. Otherwise, if the argument has integer type or the type double, (2) (cos) is called. Otherwise, (1) (cosf) is called. If the argument is complex, then the macro invokes the corresponding complex function (ccosf, ccos, ccosl).
The functions (4-6) are declared if and only if the implementation predefines __STDC_IEC_60559_DFP__ (i.e. the implementation supports decimal floating-point numbers). (since C23)

Contents

[edit] Parameters

arg - floating-point value representing angle in radians

[edit] Return value

If no errors occur, the cosine of arg (cos(arg)) in the range [-1 ; +1], is returned.

The result may have little or no significance if the magnitude of arg is large. (until C99)

If a domain error occurs, an implementation-defined value is returned (NaN where supported).

If a range error occurs due to underflow, the correct result (after rounding) is returned.

[edit] Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

[edit] Notes

The case where the argument is infinite is not specified to be a domain error in C, but it is defined as a domain error in POSIX.

[edit] Example

#include <errno.h> #include <fenv.h> #include <math.h> #include <stdio.h>   #ifndef GNUC #pragma STDC FENV_ACCESS ON #endif   int main(void) { const double pi = acos(-1);   // typical usage printf("cos(pi/3) = %f\n", cos(pi / 3)); printf("cos(pi/2) = %f\n", cos(pi / 2)); printf("cos(-3*pi/4) = %f\n", cos(-3 * pi / 4));   // special values printf("cos(+0) = %f\n", cos(0.0)); printf("cos(-0) = %f\n", cos(-0.0));   // error handling feclearexcept(FE_ALL_EXCEPT); printf("cos(INFINITY) = %f\n", cos(INFINITY)); if (fetestexcept(FE_INVALID)) puts(" FE_INVALID raised"); }

Possible output:

cos(pi/3) = 0.500000 cos(pi/2) = 0.000000 cos(-3*pi/4) = -0.707107 cos(+0) = 1.000000 cos(-0) = 1.000000 cos(INFINITY) = -nan FE_INVALID raised

[edit] References

[edit] See also