# std::proj<div class="t-tr-text">(Std :: complex)<div class="t-tr-dropdown"><div><div><div class="t-tr-dropdown-arrow-border"></div><div class="t-tr-dropdown-arrow"></div><div class="t-tr-dropdown-h">Original:</div><div class="t-tr-dropdown-orig">(std::complex)</div><div class="t-tr-dropdown-notes">The text has been machine-translated via [http://translate.google.com Google Translate].<br/> You can help to correct and verify the translation. Click [http://en.cppreference.com/w/Cppreference:MachineTranslations here] for instructions.</div></div></div></div></div>

< cpp‎ | numeric‎ | complex

C++
 Sprache Concepts Utilities-Bibliothek Strings Bibliothek Container-Bibliothek Algorithmen-Bibliothek Iteratoren Bibliothek Numerik-Bibliothek Input / Output-Bibliothek Lokalisierungen Bibliothek Reguläre Ausdrücke Bibliothek (C++11) Atomare Operationen Bibliothek (C++11) Thread Support-Bibliothek (C++11)

Numerik-Bibliothek
Gemeinsame mathematischen Funktionen
Floating-Point-Umgebung
Komplexe Zahlen
Numerische Arrays
Pseudo-Zufallszahlen
Compile-time rationale Arithmetik (C++11)
Generische numerische Operationen
Original:
Generic numeric operations
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 iota (C++11)
 accumulate
 inner_product
 partial_sum

Komplexe Zahlen
Member-Funktionen
Original:
Member functions
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 complex::complex
 complex::operator=
 complex::real
 complex::imag
 complex::operator+=complex::operator-=complex::operator*=complex::operator/=
Non-Member-Funktionen
Original:
Non-member functions
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 operator==operator!=
 operator<>
 real
 imag
 abs
 arg
 norm
 conj
 proj (C++11)
 polar
Exponentialfunktionen
Original:
Exponential functions
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 exp
 log
 log10
Power-Funktionen
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Power functions
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 pow
 sqrt
Trigonometrische Funktionen
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Trigonometric functions
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 sin
 cos
 tan
 asin (C++11)
 acos (C++11)
 atan (C++11)
Hyperbolische Funktionen
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Hyperbolic functions
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 sinh
 cosh
 tanh
 asinh (C++11)
 acosh (C++11)
 atanh (C++11)

 Defined in header template< class T > complex proj( const complex& z ); (seit C++11)
Gibt die Projektion der komplexen Zahl `z` auf die Riemannsche .
Original:
Returns the projection of the complex number `z` onto the Riemann sphere.
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Für die meisten `z`, std::proj(z)==z, aber alle komplexen Unendlichkeiten, selbst wenn die Zahl eine Komponente unendlich ist und das andere ist NaN, positive reelle Unendlichkeit (INFINITY, 0) oder (INFINITY, -0) geworden. Das Vorzeichen der imaginären (Null)-Komponente ist das Zeichen std::imag(z) .
Original:
For most `z`, std::proj(z)==z, but all complex infinities, even the numbers where one component is infinite and the other is NaN, become positive real infinity, (INFINITY, 0) or (INFINITY, -0). The sign of the imaginary (zero) component is the sign of std::imag(z).
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## Inhaltsverzeichnis

### [Bearbeiten]Parameter

 z - komplexen WertOriginal: complex valueThe text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

### [Bearbeiten]Rückgabewert

die Projektion des `z` auf der Riemannschen Kugel
Original:
the projection of `z` onto the Riemann sphere
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### [Bearbeiten]Beispiel

```#include <iostream>
#include <complex>

int main()
{
std::complex<double> c1(1, 2);
std::cout << "proj" << c1 << " = " << std::proj(c1) << '\n';

std::complex<double> c2(INFINITY, -1);
std::cout << "proj" << c2 << " = " << std::proj(c2) << '\n';

std::complex<double> c3(0, -INFINITY);
std::cout << "proj" << c3 << " = " << std::proj(c3) << '\n';
}```

Output:

```proj(1,2) = (1,2)
proj(inf,-1) = (inf,-0)
proj(0,-inf) = (inf,-0)```

### [Bearbeiten]Siehe auch

 abs(std::complex) liefert den Betrag einer komplexen Zahl Original: returns the magnitude of a complex number The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template)  norm gibt die quadrierte Größe Original: returns the squared magnitude The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template)  polar konstruiert eine komplexe Zahl von Betrag und Phasenwinkel Original: constructs a complex number from magnitude and phase angle The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template)