# tan() function for complex number in C++

In this article we will be discussing the working, syntax and examples of tan() function for complex numbers in C++ STL.

tan() for complex numbers is a function which comes under the <complex> header file. This function is used to find the tangent of the complex number associated with it. This function is the complex version of simple tan() which comes under <cmath> header file.

## What are complex numbers?

Complex numbers are the numbers which are the combination of real number and imaginary number.

They are written as: a+bi

Where a and b are the real numbers and i is an imaginary number.

## Syntax

template<class T> complex<T> tan (const complex<T>& num);

## Parameters

The function accepts only one parameter which is num, which is an complex value.

## Return value

It returns the tangent value of num.

## Example

Input: complex <double> num(0.0, 1.0);
tan(num);
Output: (0, 1.55741)

## Example

Live Demo

#include <iostream>
#include <complex>
using namespace std;
int main () {
complex<double> tan_num(9.1, 2.6);
cout<<"tan of "<<tan_num<<" is "<<tan(tan_num);
return 0;
}

## Output

If we run the above code it will generate the following output −

tan of (9.1, 2.6) is (-0.00661488, 0.99123)

## Example

Live Demo

#include <iostream>
#include <complex>
using namespace std;
int main () {
complex<double> tan_num(1.0, 0.0);
cout<<"tan of "<<tan_num<<" is "<<tan(tan_num);
return 0;
}

## Output

If we run the above code it will generate the following output −

tan of (1, 0) is (1.55741, 0)