tan, tanf, tanl
<math.h>
<tgmath.h>
tanl) is called. Otherwise, if the argument has integer type or the type double, (2) (tan) is called. Otherwise, (1) (tanf) is called. If the argument is complex, then the macro invokes the corresponding complex function (ctanf , ctan , ctanl ).The functions (4-6) are declared if and only if the implementation predefines __STDC_IEC_60559_DFP__ (i.e. the implementation supports decimal floating-point numbers).
[edit] Parameters
[edit] Return value
If no errors occur, the tangent of arg (tan(arg)) is returned.
The result may have little or no significance if the magnitude of arg is large.
(until C99)If a domain error occurs, an implementation-defined value is returned (NaN where supported).
If a range error occurs due to underflow, the correct result (after rounding) is returned.
[edit] Error handling
Errors are reported as specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559):
- if the argument is ±0, it is returned unmodified;
- if the argument is ±∞, NaN is returned and FE_INVALID is raised;
- if the argument is NaN, NaN is returned.
[edit] Notes
The case where the argument is infinite is not specified to be a domain error in C, but it is defined as a domain error in POSIX.
The function has mathematical poles at π(1/2 + n); however no common floating-point representation is able to represent π/2 exactly, thus there is no value of the argument for which a pole error occurs.
[edit] Example
#include <errno.h> #include <fenv.h> #include <math.h> #include <stdio.h> #ifndef __GNUC__ #pragma STDC FENV_ACCESS ON #endif int main(void) { const double pi = acos (-1); // typical usage printf ("tan(pi*1/4) = %+f\n", tan(pi * 1 / 4)); // 45 deg printf ("tan(pi*3/4) = %+f\n", tan(pi * 3 / 4)); // 135 deg printf ("tan(pi*5/4) = %+f\n", tan(pi * 5 / 4)); // -135 deg printf ("tan(pi*7/4) = %+f\n", tan(pi * 7 / 4)); // -45 deg // special values printf ("tan(+0) = %f\n", tan(0.0)); printf ("tan(-0) = %f\n", tan(-0.0)); // error handling feclearexcept (FE_ALL_EXCEPT ); printf ("tan(INFINITY) = %f\n", tan(INFINITY)); if (fetestexcept (FE_INVALID )) puts (" FE_INVALID raised"); }
Possible output:
tan(pi*1/4) = +1.000000 tan(pi*3/4) = -1.000000 tan(pi*5/4) = +1.000000 tan(pi*7/4) = -1.000000 tan(+0) = 0.000000 tan(-0) = -0.000000 tan(INFINITY) = -nan FE_INVALID raised
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.12.4.7 The tan functions (p: TBD)
- 7.25 Type-generic math <tgmath.h> (p: TBD)
- F.10.1.7 The tan functions (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.12.4.7 The tan functions (p: 175)
- 7.25 Type-generic math <tgmath.h> (p: 272-273)
- F.10.1.7 The tan functions (p: 378)
- C11 standard (ISO/IEC 9899:2011):
- 7.12.4.7 The tan functions (p: 240)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.1.7 The tan functions (p: 519)
- C99 standard (ISO/IEC 9899:1999):
- 7.12.4.7 The tan functions (p: 220)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- F.9.1.7 The tan functions (p: 457)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.5.2.7 The tan function