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)
   961287335215343.37500 ulp for y1(2.19714132603101708) = 2.21708714867389158e-17)
   717597815920711.75000 ulp for y1(2.19714132603101664) = -1.88452407637280825e-16)
   666159534559479.25000 ulp for y1(11.7491548308398812) = 7.36299775890936191e-18)
   209680847855586.12500 ulp for y1(5.4296810407941356) = -1.65774312049122376e-16)
   55821467960618.77344 ulp for y1(43.1882180973932108) = 5.40741495537015435e-17)
   53684065437732.47656 ulp for y1(8.59600586833116864) = -7.77993070896235658e-17)
   52568239668605.92969 ulp for y1(30.6182864916411148) = -1.54065511975555398e-17)
   40512534618768.54688 ulp for y1(2.19714132603101486) = -1.12325537644959865e-15)
   36294127052720.22656 ulp for y1(27.4752949804492239) = 6.15714287015702358e-17)
   34176146190834.93750 ulp for y1(14.897442128336726) = 1.26260989918320133e-16)
   28330537878704.99219 ulp for y1(21.1880689341422119) = -1.88917969179349792e-16)
   22102051212723.20312 ulp for y1(5.42968104079413472) = 1.4111300617307099e-16)
   21474232142907.52344 ulp for y1(18.0434022767278535) = 3.9580137065772002e-16)
   20243869873772.79297 ulp for y1(14.8974421283367242) = -2.40484789428017261e-16)
   17700275902175.60938 ulp for y1(18.043402276727857) = -2.7307779446455321e-16)
   15561978589993.88477 ulp for y1(52.6145507671729575) = -2.98103463953301222e-17)
   13921541080890.78906 ulp for y1(8.59600586833117042) = 4.05758394758811353e-16)
   13333557429769.64844 ulp for y1(2.19714132603100687) = -5.28368801786747866e-15)

<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>