ACOS

Returns the inverse cosine value of a numeric expression

Syntax

ACOS( expr )

Arguments

Parameter Description
expr Numeric expression in range [-1.0, 1.0]

Returns

Always returns a floating point result of the inverse cosine, in radians.

Notes

  • Valid inputs for an inverse cosine are in the range [ -1.0 , 1.0]. Inputs exceeding this range will result in an error.
  • The result is given in radians, in the range [0, π].
  • If the input value is NULL, the result is NULL.

Examples

For these examples, consider the following table and contents:

CREATE TABLE trig(i INT, f DOUBLE);

INSERT INTO trig VALUES (0,0.0), (1,-0.866)
, (2,-0.707), (3,-0.5)
, (4,0.5), (5,0.707)
, (6, 0.866), (7, 1);

Inverse cosine of 0 (= π/2)

numbers=> SELECT ACOS(0);
acos
-------------------
1.5707963267948966

Computing inverse cosine for a column

numbers=> SELECT f, ACOS(f) FROM trig;
f     | acos
------+-----
    0 | 1.57
-0.87 | 2.62
-0.71 | 2.36
 -0.5 | 2.09
  0.5 | 1.05
 0.71 | 0.79
 0.87 | 0.52
    1 |    0