result of y1 is never more precise than double

20 largest ulp errors (stored in a double)
   nan0x10000000 ulp for y1(-2.2250738585072019e-308) = nan0x000000000010000000)
   nan0x10000000 ulp for y1(-2.2250738585072014e-308) = nan0x000000000010000000)
   69565318932819096.00000 ulp for y1(5.4296810407941356) = 1.5543122344752192e-15)
   39289670639282528.00000 ulp for y1(5.4296810407941347) = 1.1102230246251565e-15)
   9282046390281332.00000 ulp for y1(2.1971413260310171) = -3.4694469519536142e-18)
   7506308215913360.00000 ulp for y1(5.4296810407941312) = 2.8310687127941492e-15)
   5552645232891998.00000 ulp for y1(5.4296810407941427) = -3.8857805861880479e-16)
   2968901295769475.00000 ulp for y1(11.749154830839881) = 9.1369654837514952e-18)
   1285656155062308.80000 ulp for y1(5.429681040794109) = 1.0935696792557792e-14)
   713524827601678.50000 ulp for y1(2.1971413260310149) = -9.9052710478275685e-16)
   458279714506853.50000 ulp for y1(8.5960058683311686) = -8.2786333495454029e-17)
   433957361299960.25000 ulp for y1(2.1971413260310166) = -2.1684043449710089e-16)
   200554708783951.19000 ulp for y1(5.4296810407940077) = 4.4630965589931293e-14)
   118210754823759.22000 ulp for y1(8.5960058683311704) = 3.992437695990443e-16)
   114134078042182.64000 ulp for y1(2.1971413260310069) = -5.2041704279304213e-15)
   103969502513396.92000 ulp for y1(30.618286491641115) = -1.5564943567622903e-17)
   90099782150613.92200 ulp for y1(5.4296810407934792) = 2.2548629630136929e-13)
   90098597113292.89100 ulp for y1(2.1971413260310331) = 8.4932061383824475e-15)
   53591420713021.77300 ulp for y1(43.188218097393211) = 5.4060405826432598e-17)
   51820020070927.69500 ulp for y1(24.331942571356912) = 4.7221946534596665e-17)

<tr><td align=left><a href=y1.res>y1</a></td><td align=right>987</td><td align=right>nan0x10000000</td><td>-2.2250738585072019e-308</td><td>nan0x000000000010000000</td></tr>