result of y1 is never more precise than double

20 largest ulp errors (stored in a double)
   inf ulp for y1(-2.22507385850720188e-308) = -inf)
   inf ulp for y1(-2.22507385850720138e-308) = -inf)
   2128919734961560.50000 ulp for y1(2.19714132603101708) = 3.16933072160362723e-17)
   1486343883962473.25000 ulp for y1(11.7491548308398812) = 7.9948447982825577e-18)
   648335997107835.75000 ulp for y1(2.19714132603101664) = -1.90159843296217671e-16)
   300261587981486.12500 ulp for y1(5.4296810407941356) = -1.6800729969447571e-16)
   157873329579245.21875 ulp for y1(5.42968104079413472) = 1.37765985749470099e-16)
   103969502513396.92188 ulp for y1(30.6182864916411148) = -1.55649435676229031e-17)
   77756165491232.76562 ulp for y1(43.1882180973932108) = 5.42093325642464596e-17)
   55451412736745.93750 ulp for y1(14.897442128336726) = 1.26785465731639685e-16)
   44283405712302.78906 ulp for y1(8.59600586833117042) = 4.07255350259894696e-16)
   40149044256901.60938 ulp for y1(18.043402276727857) = -2.74184604197391083e-16)
   24961953077354.48047 ulp for y1(8.59600586833116864) = -7.74452797215537627e-17)
   23908540076894.99219 ulp for y1(21.1880689341422119) = -1.88808958517199131e-16)
   22262910749942.79297 ulp for y1(14.8974421283367242) = -2.40385243027188905e-16)
   16983762551543.88477 ulp for y1(52.6145507671729575) = -2.98191088155093179e-17)
   15197192093824.64844 ulp for y1(2.19714132603100687) = -5.28221786933939098e-15)
   13289638901809.54492 ulp for y1(5.42968104079414271) = -2.58395226930103462e-15)
   12568205938916.30859 ulp for y1(24.3319425713569117) = 4.76187696147193267e-17)
   12172060416313.99609 ulp for y1(14.8974421283367224) = -6.09584519237723719e-16)

<tr><td align=left><a href=y1.res>y1</a></td><td align=right>987</td><td align=right>inf</td><td>-2.22507385850720188e-308</td><td>-inf</td></tr>