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c99 [ flag... ] file... -lm [ library... ] #include <math.h> double tan(double x);
float tanf(float x);
long double tanl(long double x);
These functions compute the tangent of their argument x, measured in radians.
Upon successful completion, these functions return the tangent of x.
If x is NaN, a NaN is returned.
If x is \(+-0, x is returned.
If x is \(+-Inf, a domain error occurs and a NaN is returned.
These functions will fail if:
Domain Error
The value of x is \(+-Inf. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised.
There are no known floating-point representations such that for a normal argument, tan(x) is either overflow or underflow.
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.
See attributes(7) for descriptions of the following attributes:
| ATTRIBUTE TYPE ATTRIBUTE VALUE |
| Interface Stability Standard |
| MT-Level MT-Safe |
math.h (3HEAD), atan (3M), feclearexcept (3M), fetestexcept (3M), isnan (3M), attributes (7), standards (7)