Originální popis anglicky:
tan, tanf, tanl - tangent function
Návod, kniha: POSIX Programmer's Manual
#include <math.h>
double tan(double
x);
float tanf(float
x);
long double tanl(long double
x);
These functions shall compute the tangent of their argument
x, measured
in radians.
An application wishing to check for error situations should set
errno to
zero and call
feclearexcept(FE_ALL_EXCEPT) before calling these
functions. On return, if
errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
non-zero, an error has occurred.
Upon successful completion, these functions shall return the tangent of
x.
If the correct value would cause underflow, and is not representable, a range
error may occur, and either 0.0 (if supported), or an
implementation-defined value shall be returned.
If
x is NaN, a NaN shall be returned.
If
x is ±0,
x shall be returned.
If
x is subnormal, a range error may occur and
x should be
returned.
If
x is ±Inf, a domain error shall occur, and either a NaN (if
supported), or an implementation-defined value shall be returned.
If the correct value would cause underflow, and is representable, a range error
may occur and the correct value shall be returned.
If the correct value would cause overflow, a range error shall occur and
tan(),
tanf(), and
tanl() shall return ±HUGE_VAL,
±HUGE_VALF, and ±HUGE_VALL, respectively, with the same sign as
the correct value of the function.
These functions shall fail if:
- Domain Error
- The value of x is ±Inf.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [EDOM]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
- Range Error
- The result overflows
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow
floating-point exception shall be raised.
These functions may fail if:
- Range Error
- The result underflows, or the value of x is
subnormal.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
floating-point exception shall be raised.
The following sections are informative.
#include <math.h>
...
double radians = 45.0 * M_PI / 180;
double result;
...
result = tan (radians);
There are no known floating-point representations such that for a normal
argument,
tan(
x) is either overflow or underflow.
These functions may lose accuracy when their argument is near a multiple of pi/2
or is far from 0.0.
On error, the expressions (math_errhandling & MATH_ERRNO) and
(math_errhandling & MATH_ERREXCEPT) are independent of each other, but at
least one of them must be non-zero.
None.
None.
atan() ,
feclearexcept() ,
fetestexcept() ,
isnan()
, the Base Definitions volume of IEEE Std 1003.1-2001, Section
4.18, Treatment of Error Conditions for Mathematical Functions,
<math.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
