result of atan is never more precise than double

3 results were exact to double the precision

20 largest ulp errors (stored in a double)
   0.53613 ulp for atan(8.12578045399999382) = 1.44834691412694605)
   0.53319 ulp for atan(-9.35034389000003685) = -1.46425336492284441)
   0.53083 ulp for atan(-9.15453677399999499) = -1.46199226615803113)
   0.51800 ulp for atan(8.06882011400000465) = 1.44749121020122962)
   0.51263 ulp for atan(-0.349726053999999453) = -0.336430748655029088)
   0.50960 ulp for atan(-0.732244161799999183) = -0.63204019076294804)
   0.50905 ulp for atan(8.12578045400000804) = 1.44834691412694649)
   0.50782 ulp for atan(-0.273385260600000402) = -0.266864381664049577)
   0.50779 ulp for atan(8.95974109599996282) = 1.4596459643933839)
   0.50684 ulp for atan(-9.15453677399997545) = -1.46199226615803113)
   0.50631 ulp for atan(0.118152693199999853) = 0.117607446782605846)
   0.50488 ulp for atan(-9.15453677399941057) = -1.46199226615802447)
   0.50442 ulp for atan(-0.789293982799994853) = -0.668178705726321986)
   0.50430 ulp for atan(9.04317894799994804) = 1.46066319437268444)
   0.50420 ulp for atan(0.254229188000000605) = 0.248955097420742177)
   0.50417 ulp for atan(-0.426553727999999799) = -0.403185932629211208)
   0.50375 ulp for atan(8.12578045400008264) = 1.44834691412694738)
   0.50362 ulp for atan(0.350766107599999211) = 0.337357157489676651)
   0.50240 ulp for atan(0.118152693200000852) = 0.117607446782606817)
   0.50234 ulp for atan(-0.758092139999989256) = -0.648659994165775133)

<tr><td align=left><a href=atan.res>atan</a></td><td align=right>870</td><td align=right>0.53613</td><td>8.12578045399999382</td><td>1.44834691412694605</td></tr>