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c++complex-numbers
QuantumDot
QuantumDot

Reputation: 435

How to enter complex number in an expression in C++

In C, I am able to use complex numbers inside of an expression using CMPLX:

#include <complex.h>

int main(){

    double _Complex result;
    //complicated code
    result = ((3.1*CMPLX(0.,1.))+2.);

return 0;
}

How do I do the same in C++?

#include <complex>

int main(){

    std::complex<double> result;
    //complicated code
    result = ((3.1*???(0.,1.))+2.);   // what to put in '???'

return 0;
}

Is there something short I can put in for ???? I don't want to write it with a + operation: 0.0 + 1.0 I.

Upvotes: 0

Views: 520

Answers (2)

Galik
Galik

Reputation: 48615

You can create a type alias to make the std::complex type easier to use.

For example:

#include <complex>
#include <iostream>

// create a type alias
using CMPLX = std::complex<double>;

int main()
{
    // use it the same way you did in `C`
    auto result = ((3.1 * CMPLX(0.0, 1.0)) + 2.0);

    std::cout << "result: " << result << '\n';
}

Output:

result: (2,3.1)

Upvotes: 1

Passer By
Passer By

Reputation: 21131

The simplest would be to use user defined literals to create a complex literal

#include<complex>
using namespace std::literals;

auto result = (3.1 * 1if) + 2;

Or if you don't have C++14, calling the constructor of a class will create a temporary

auto result = (3.1 * std::complex<double>{0, 1}) + 2;

Upvotes: 2

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