std::tan,std::tanf,std::tanl (3) - Linux Manuals

std::tan,std::tanf,std::tanl: std::tan,std::tanf,std::tanl


std::tan,std::tanf,std::tanl - std::tan,std::tanf,std::tanl


Defined in header <cmath>
float tan ( float arg );
float tanf( float arg ); (since C++11)
double tan ( double arg ); (1) (2)
long double tan ( long double arg );
long double tanl( long double arg ); (3) (since C++11)
double tan ( IntegralType arg ); (4) (since C++11)

1-3) Computes the tangent of arg (measured in radians).
4) A set of overloads or a function template accepting an argument of any integral_type. Equivalent to 2) (the argument is cast to double).


arg - value representing angle in radians, of a floating-point or Integral_type

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 C++11)

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.

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


The case where the argument is infinite is not specified to be a domain error in C (to which C++ defers), 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.


// Run this code

  #include <iostream>
  #include <cmath>
  #include <cerrno>
  #include <cfenv>

  const double pi = std::acos(-1);
  int main()
      // typical usage
      std::cout << "tan (pi/4) = " << std::tan( pi/4) << '\n' // 45 deg.
                << "tan(3*pi/4) = " << std::tan(3*pi/4) << '\n' // 135 deg
                << "tan(5*pi/4) = " << std::tan(5*pi/4) << '\n' // -135 deg
                << "tan(7*pi/4) = " << std::tan(7*pi/4) << '\n'; // -45 deg
      // special values
      std::cout << "tan(+0) = " << std::tan(0.0) << '\n'
                << "tan(-0) = " << std::tan(-0.0) << '\n';
      // error handling
      std::cout << "tan(INFINITY) = " << std::tan(INFINITY) << '\n';
      if (std::fetestexcept(FE_INVALID))
          std::cout << " FE_INVALID raised\n";

Possible output:

  tan (pi/4) = 1
  tan(3*pi/4) = -1
  tan(5*pi/4) = 1
  tan(7*pi/4) = -1
  tan(+0) = 0
  tan(-0) = -0
  tan(INFINITY) = -nan
      FE_INVALID raised

See also

sinl computes sine (sin(x))


cosl computes cosine (cos(x))


atanl computes arc tangent (arctan(x))

                   computes tangent of a complex number (tan(z))
tan(std::complex) (function template)
                   applies the function std::tan to each element of valarray
tan(std::valarray) (function template)