std:: arg (std::complex)
From cppreference.com
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Defined in header
<complex>
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template
<
class
T
>
T arg ( const std:: complex < T > & z ) ; |
(1) | |
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Additional overloads
(since C++11)
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Defined in header
<complex>
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| (A) | ||
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float
arg
(
float
f
)
;
double
arg
(
double
f
)
;
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(until C++23) | |
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template
<
class
FloatingPoint
>
FloatingPoint
|
(since C++23) | |
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template
<
class
Integer
>
double arg ( Integer i ) ; |
(B) | |
1)
Calculates the phase angle (in radians) of the complex number
z
.
|
A,B)
Additional overloads are provided for all integer and floating-point types, which are treated as complex numbers with zero imaginary component.
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(since C++11) |
Parameters
| z | - | complex value |
| f | - | floating-point value |
| i | - | integer value |
Return value
1)
std::
atan2
(
std::
imag
(
z
)
,
std::
real
(
z
)
)
. If no errors occur, this is the phase angle of
z
in the interval
[−π; π]
.
A)
Zero if
f
is positive or +0,
π
if
f
is negative or -0, NaN otherwise.
B)
Zero if
i
is non-negative,
π
if it is negative.
Notes
The additional overloads are not required to be provided exactly as (A,B) . They only need to be sufficient to ensure that for their argument num :
-
If
num
has a
standard
(until C++23)
floating-point type
T, then std :: arg ( num ) has the same effect as std :: arg ( std:: complex < T > ( num ) ) . - Otherwise, if num has an integer type, then std :: arg ( num ) has the same effect as std :: arg ( std:: complex < double > ( num ) ) .
Example
Run this code
#include <complex> #include <iostream> int main() { std::complex<double> z1(1, 0); std::complex<double> z2(0, 0); std::complex<double> z3(0, 1); std::complex<double> z4(-1, 0); std::complex<double> z5(-1, -0.0); double f = 1.; int i = -1; std::cout << "phase angle of " << z1 << " is " << std::arg(z1) << '\n' << "phase angle of " << z2 << " is " << std::arg(z2) << '\n' << "phase angle of " << z3 << " is " << std::arg(z3) << '\n' << "phase angle of " << z4 << " is " << std::arg(z4) << '\n' << "phase angle of " << z5 << " is " << std::arg(z5) << " " "(the other side of the cut)\n" << "phase angle of " << f << " is " << std::arg(f) << '\n' << "phase angle of " << i << " is " << std::arg(i) << '\n'; }
Output:
phase angle of (1,0) is 0 phase angle of (0,0) is 0 phase angle of (0,1) is 1.5708 phase angle of (-1,0) is 3.14159 phase angle of (-1,-0) is -3.14159 (the other side of the cut) phase angle of 1 is 0 phase angle of -1 is 3.14159
See also
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returns the magnitude of a complex number
(function template) |
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constructs a complex number from magnitude and phase angle
(function template) |
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(C++11)
(C++11)
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arc tangent, using signs to determine quadrants
(function) |
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applies the function
std::atan2
to a valarray and a value
(function template) |
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C documentation
for
carg
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