acos -- arccosine

• Usage:

  acos x

  acos I

• Inputs:
  • x
  • I, a real interval
• Outputs:
  • a number, the arccosine (in radians) of x
  • a real interval, an interval containing the arccosines of the points of I

i1 : acos 0.5

o1 = 1.047197551196598

o1 : RR (of precision 53)