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std::tan

From cppreference.com
< cpp‎ | numeric‎ | math
 
 
 
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Defined in header <cmath>
float       tan( float arg );
(1)
double      tan( double arg );
(2)
long double tan( long double arg );
(3)
double      tan( Integral arg );
(4) (since C++11)

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).

Contents

[edit] Parameters

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

[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 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.

[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 (to which C++ defers), but it is defined as a domain error in POSIX

[edit] Example

#include <iostream>
#include <cmath>
#include <cerrno>
#include <cfenv>
 
#pragma STDC FENV_ACCESS ON
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::feclearexcept(FE_ALL_EXCEPT);
    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

[edit] See also

computes sine (sin(x))
(function) [edit]
computes cosine (cos(x))
(function) [edit]
computes arc tangent (arctan(x))
(function) [edit]
computes tangent of a complex number (tan(z))
(function template) [edit]
applies the function std::tan to each element of valarray
(function template) [edit]