result of acosh is never more precise than double

20 largest ulp errors (stored in a double)
   25216050.55323 ulp for acosh(1.00000000000000022) = 2.10734243388799281e-08)
   5527209.72640 ulp for acosh(1.00000000000000244) = 6.98926412301403314e-08)
   329972.45396 ulp for acosh(1.0000000000000866) = 4.16166783701032079e-07)
   8.49989 ulp for acosh(1.00754871629994835) = 0.122794447636203591)
   7.49996 ulp for acosh(1.00782267782507762) = 0.124999999994947333)
   6.48954 ulp for acosh(1.00754871629999632) = 0.122794447636593224)
   4.99966 ulp for acosh(1.00782267782562651) = 0.1249999999993269)
   4.49995 ulp for acosh(1.00754871630097775) = 0.122794447644565721)
   4.49990 ulp for acosh(1.00754871629801723) = 0.122794447620516639)
   4.00394 ulp for acosh(1.00782267781110768) = 0.124999999883478305)
   3.91277 ulp for acosh(1.03141309987957275) = 0.249999999999998196)
   3.50018 ulp for acosh(1.00782267782568757) = 0.124999999999814246)
   3.49997 ulp for acosh(1.00782267782648072) = 0.125000000006142947)
   3.49770 ulp for acosh(1.00754871628913567) = 0.122794447548369406)
   3.00002 ulp for acosh(1.03141309987688334) = 0.249999999989352018)
   2.74993 ulp for acosh(1.0078226778258097) = 0.12500000000078873)
   2.56611 ulp for acosh(1.00754871629999676) = 0.122794447636596957)
   2.53500 ulp for acosh(1.1209539299999991) = 0.487014035561032566)
   2.50873 ulp for acosh(1.00754871629998832) = 0.122794447636528414)
   2.50456 ulp for acosh(1.00782267782574531) = 0.125000000000274919)

<tr><td align=left><a href=acosh.res>acosh</a></td><td align=right>1033</td><td align=right>25216050.55323</td><td>1.00000000000000022</td><td>2.10734243388799281e-08</td></tr>