PostgreSQL ACOS() Function

The PostgreSQL ACOS() function returns arc cosine of a value. The returned value will be in the range 0 through 𝜋. The other variant of this function is ACOSD() which returns the result in degrees.

If the argument is not within the range of -1 to 1, then this function returns an error.

Note: ACOS() is the inverse of COS().

Syntax

/* returns result in radians */
ACOS(x)

/* returns result in degrees */
ACOSD(x)

Parameters

Return Value

Returns the arc cosine of the value.

Example 1:

The example below shows the usage of ACOS() function.

SELECT ACOS(0.2);
Result: 1.369438406004566

SELECT ACOS(0.8);
Result: 0.6435011087932843

SELECT ACOS(1);
Result: 0

SELECT ACOS(-1);
Result: 3.141592653589793

SELECT ACOS(0);
Result: 1.5707963267948966

SELECT ACOS(-0.2);
Result: 1.7721542475852274

SELECT ACOSD(-0.2);
Result: 101.53695903281549

SELECT ACOSD(-1);
Result: 180

Example 2:

Consider a database table called Sample with the following records:

The statement given below can be used to calculate the arc cosine of records of column x.

SELECT *, ACOS(x) AS ACOS_Value FROM Sample;

This will produce the result as shown below: