std::atan, std::atanf, std::atanl
Defined in header <cmath> |
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| (1) | ||
float atan ( float arg ); |
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float atanf( float arg ); |
(since C++11) | |
double atan ( double arg ); |
(2) | |
| (3) | ||
long double atan ( long double arg ); |
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long double atanl( long double arg ); |
(since C++11) | |
double atan ( IntegralType arg ); |
(4) | (since C++11) |
1-3) Computes the principal value of the arc tangent of
arg
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).
Parameters
| arg | - | value of a floating-point or Integral type |
Return value
If no errors occur, the arc tangent ofarg (arctan(arg)) in the range [-
π/2 , +
π/2] radians, is returned.
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 +∞, +π/2 is returned
- If the argument is -∞, -π/2 is returned
- if the argument is NaN, NaN is returned
Notes
POSIX specifies that in case of underflow, arg is returned unmodified, and if that is not supported, an implementation-defined value no greater than DBL_MIN, FLT_MIN, and LDBL_MIN is returned.
Examples
#include <iostream>
#include <cmath>
int main()
{
std::cout << "atan(1) = " << atan(1) << " 4*atan(1) = " << 4*atan(1) << '\n';
// special values
std::cout << "atan(Inf) = " << atan(INFINITY)
<< " 2*atan(Inf) = " << 2*atan(INFINITY) << '\n'
<< "atan(-0.0) = " << atan(-0.0) << '\n'
<< "atan(+0.0) = " << atan(0) << '\n';
}
Output:
atan(1) = 0.785398 4*atan(1) = 3.14159 atan(Inf) = 1.5708 2*atan(Inf) = 3.14159 atan(-0.0) = -0 atan(+0.0) = 0
See also
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(C++11)(C++11)
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computes arc sine (\({\small\arcsin{x} }\)arcsin(x)) (function) |
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(C++11)(C++11)
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computes arc cosine (\({\small\arccos{x} }\)arccos(x)) (function) |
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(C++11)(C++11)
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arc tangent, using signs to determine quadrants (function) |
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(C++11)(C++11)
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computes tangent (\({\small\tan{x} }\)tan(x)) (function) |
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(C++11)
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computes arc tangent of a complex number (\({\small\arctan{z} }\)arctan(z)) (function template) |
applies the function std::atan to each element of valarray (function template) |
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C documentation for atan |
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