In the Perl programming language has a built-in function `atan2()`

.
The main purpose of the function is the conversion from Cartesian coordinate system to polar.

This program displays `1.26879861219712`

.

```
my $value = atan2($y, $x);
```

Arguments to Perl function `atan2()`

— two numbers.

If the functions `atan2()`

do not pass any argument, or pass exactly one argument, it will error:

```
Not enough arguments for atan2 at script.pl line 3, near "atan2()"
Execution of script.pl aborted due to compilation errors.
```

The function uses the default variable `$_`

.
If there is a need to use it, then it must be explicitly passed to the function `atan2($_, 1);`

If the functions `atan2()`

can pass more than two arguments, it will error:

```
Too many arguments for atan2 at script.pl line 3, near "3)"
Execution of script.pl aborted due to compilation errors.
```

Function `atan2()`

always returns a number. `atan2($y, $x)`

returns the arctangent from `$y/$x`

.
The range of possible values is `-π`

, to `π`

, i.e., from `-3.14159265358979`

to `3.14159265358979`

.

Here is the output of the command `perldoc -f atan2`

:

```
atan2 Y,X
Returns the arctangent of Y/X in the range -PI to PI.
For the tangent operation, you may use the "Math::Trig::tan"
function, or use the familiar relation:
sub tan { sin($_[0]) / cos($_[0]) }
The return value for "atan2(0,0)" is implementation-defined;
consult your atan2(3) manpage for more information.
Portability issues: "atan2" in perlport.
```