How Atan() Works in PostgreSQL

In PostgreSQL, atan() is a mathematical function that returns the angle, in radians, whose tangent is a specified expression.

In trigonometry, this is known as the arctangent. The arctangent is the inverse of the tangent.

The arctangent is used when you know what the tangent of an angle is, but you want to know what the actual angle is.

Syntax

The syntax goes like this:

atan(x)

Where x is a double precision value that represents the tangent of the angle you’re trying to determine.

Here’s an example to demonstrate how it works.

SELECT atan(1);

Result:

0.7853981633974483

As mentioned, the argument represents the tangent, which itself can be returned with the tan() function.

Therefore, we can do the following to verify this.

SELECT atan(tan(1));

Result:

The argument can contain a fractional component.

SELECT atan(1.6197);

Result:

1.0176820992229842

The argument can also be negative.

SELECT atan(-1.6197);

Result:

-1.0176820992229842

The argument can include expressions.

SELECT atan(.5 * .45);

Result:

0.2213144423477913

As mentioned, atan() returns its argument in radians. To get it in degrees, use the atand() function.

The atand() function works exactly the same as atan(), except that its argument is returned in degrees instead of radians.