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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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TAN(3P) POSIX Programmer's Manual TAN(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
tan, tanf, tanl — tangent function
#include <math.h>
double tan(double x);
float tanf(float x);
long double tanl(long double x);
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
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 tan(), tanf(), and
tanl() shall return 0.0, or (if IEC 60559 Floating-Point is not
supported) an implementation-defined value no greater in
magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.
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 not returned, tan(), tanf(), and tanl() shall return an
implementation-defined value no greater in magnitude than
DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.
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.
Taking the Tangent of a 45-Degree Angle
#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 π/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(3p), feclearexcept(3p), fetestexcept(3p), isnan(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.20,
Treatment of Error Conditions for Mathematical Functions,
math.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 TAN(3P)
Pages that refer to this page: math.h(0p), atan2(3p), atan(3p), cos(3p), tanh(3p), tanl(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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