## What is atan in c programming?

atan in c is a mathematical function which is used to find arc tangent value of a given number in radians.

This function is defined in math.h header file.

### Prototype

```
#include<math.h>
double atan(double y);
```

### Parameter

atan function takes floating point value as angle in radians.

### Return value

This function returns arc tangent of a given number.

## Example program for atan in c

```
#include <stdio.h>
#include <math.h>
#define PI 3.14
int main()
{
double x, res, val1;
x=15.0;
val1=PI/180;
res=atan(x*val1);
printf("The arc tan of %lf is %lf degrees", x, res);
return 0;
}
```

While using gcc use below command to add math header.

`gcc file_name.c -lm`

### Code explanation

The variable val1 is converted in terms of degrees and passed along with input value to atan function. The arc tangent value is being printed onto the console.

## Difference between atan and tan in c

atan in c is a mathematical function that is used to find the arc tangent value of a given number in radians. tan in c is a mathematical function that is used to find the tangent of a given number.

Prototypes are as follows

```
double atan(double y);
double tan(double y);
```

atan( ) | tan( ) |

Used to find arc tangent of a given number. | Used to find tangent of a given number. |

`double atan(double y);` | `double tan(double y);` |

## Difference between atan and tanh in c

atan in c is a mathematical function that is used to find the arc tangent value of a given number in radians. tanh in c is used to find the hyperbolic tangent of a given number.

Prototypes are as follows

```
double atan(double y);
double tanh(double y);
```

atan in c | tanh in c |

Used to find arc tangent of given number | Used to find hyperbolic tangent of given number. |

`double atan(double y);` | `double tanh(double y);` |

## People also ask for

### What is atan in c?

atan in c is a mathematical function that is used to find the arc tangent value of a given number in radians. It is defined in math.h header file.