float tanf( float arg );
(1) (since C99)double tan( double arg );
(2)long double tanl( long double arg );
(3) (since C99)_Decimal32 tand32( _Decimal32 arg );
(4) (since C23)_Decimal64 tand64( _Decimal64 arg );
(5) (since C23)_Decimal128 tand128( _Decimal128 arg );
(6) (since C23)#define tan( arg )
(7) (since C99)1-6) Computes the tangent of arg (measured in radians).
7)Type-generic macro: If the argument has type
long double,
(3)(
tanl
) is called. Otherwise, if the argument has integer type or the type
double,
(2)(
tan
) is called. Otherwise,
(1)(
tanf
) is called. If the argument is complex, then the macro invokes the corresponding complex function (
ctanf,
ctan,
ctanl).
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).
If no errors occur, the tangent of arg (tan(arg)) 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 handlingErrors are reported as specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559):
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.
The function has mathematical poles at π(1/2 + n); however no common floating-point representation is able to represent π/2 exactly, thus there is no value of the argument for which a pole error occurs.
#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("tan(pi*1/4) = %+f\n", tan(pi * 1 / 4)); // 45 deg
printf("tan(pi*3/4) = %+f\n", tan(pi * 3 / 4)); // 135 deg
printf("tan(pi*5/4) = %+f\n", tan(pi * 5 / 4)); // -135 deg
printf("tan(pi*7/4) = %+f\n", tan(pi * 7 / 4)); // -45 deg
// special values
printf("tan(+0) = %f\n", tan(0.0));
printf("tan(-0) = %f\n", tan(-0.0));
// error handling
feclearexcept(FE_ALL_EXCEPT);
printf("tan(INFINITY) = %f\n", tan(INFINITY));
if (fetestexcept(FE_INVALID))
puts(" FE_INVALID raised");
}
Possible output:
tan(pi*1/4) = +1.000000
tan(pi*3/4) = -1.000000
tan(pi*5/4) = +1.000000
tan(pi*7/4) = -1.000000
tan(+0) = 0.000000
tan(-0) = -0.000000
tan(INFINITY) = -nan
FE_INVALID raised[edit] References
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