tan(3p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

TAN(3P)                 POSIX Programmer's Manual                TAN(3P)

PROLOG         top

       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.

NAME         top

       tan, tanf, tanl — tangent function

SYNOPSIS         top

       #include <math.h>

       double tan(double x);
       float tanf(float x);
       long double tanl(long double x);

DESCRIPTION         top

       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.

RETURN VALUE         top

       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.

ERRORS         top

       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.

EXAMPLES         top

   Taking the Tangent of a 45-Degree Angle
           #include <math.h>
           ...
           double radians = 45.0 * M_PI / 180;
           double result;
           ...
           result = tan (radians);

APPLICATION USAGE         top

       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.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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)