Acos

acos(float fValue)
The acos function returns the arccosine of number.

float acos(float fValue)

Arguments

 * float fFloat
 * The number to return the arccosine of.

Remarks
In trigonometry, acos (Arc Cosine) is the inverse of the cosine function. See cos.

This function returns a value from 0.0 to 180.0.

If fFloat > 1.0 or fFloat < -1.0, acos returns a value of 0.

Example
float x=45.0; float y=cos(x); float z=acos(y);
 * y = 0.7071...
 * z = 45.0