Computes the tangent.
#include <math.h>
float tanf (x)
float x;
long double tanl (x)
long double x;
double tan (x)
double x;_Decimal32 tand32 (x)
_Decimal32 x;
_Decimal64 tand64 (x)
_Decimal64 x;
_Decimal128 tand128 (x)
_Decimal128 x;The tan, tanf, tanl, tand32, tand64, and tand128 subroutines compute the tangent of the x parameter, measured in radians.
An application wishing to check for error situations should set the errno global variable to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. Upon return, if errno is nonzero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is nonzero, an error has occurred.
| Item | Description |
|---|---|
| x | Specifies the value to be computed. |
Upon successful completion, the tan, tanf, tanl, tand32, tand64, and tand128 subroutines return the tangent of x.
If the correct value would cause underflow, and is not representable, a range error may occur, and 0.0 is returned.
If x is NaN, a NaN is returned.
If x is ±0, x is returned.
If x is subnormal, a range error may occur and x should be returned.
If x is ±Inf, a domain error occurs, and a NaN returned.
If the correct value would cause underflow, and is representable, a range error may occur and the correct value is returned.
If the correct value would cause overflow, a range error occurs and the tan, tanf, tanl, tand32, tand64, and tand128 subroutines return the value of the macro HUGE_VAL, HUGE_VALF, HUGE_VALL, HUGE_VAL_D32, HUGE_VAL_D64, and HUGE_VAL_D128 respectively.
The tan, tanf, and tanl subroutines lose accuracy when passed a large value for the x parameter. Since the machine value of pi can only approximate its infinitely precise value, the remainder of x/(2 * pi) becomes less accurate as x becomes larger. Similar loss of accuracy occurs for the tan, tanf, and tanl subroutines during argument reduction of large arguments.