Computes the tangent.
#include <math.h> float tanf (x) float x; long double tanl (x) long double x; double tan (x) double x;
The tan, tanf, and tanl 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.
| x | Specifies the value to be computed. |
Upon successful completion, the tan, tanf, and tanl 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, and tanl subroutines return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, 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.
atanf or atanl Subroutine, feclearexcept Subroutine, fetestexcept Subroutine, and class, _class, finite, isnan, or unordered Subroutines in AIX 5L Version 5.2 Technical Reference: Base Operating System and Extensions Volume 1.
math.h in AIX 5L Version 5.2 Files Reference.