Routine Name:	acos

Description:	Returns angle (in radians) corresponding to given cosine.

Usage:		angle-in-radians = {acos cosine}

Example:	genesis >  echo { acos 1 }
		0

		genesis >  float degrees_per_radian = 360 / (2 * 3.1415926)
		genesis >  echo {{ acos 0.707} * degrees_per_radian}
		45.00865245

Notes:		

See also:	cos


