result of sqrt is never more precise than double

2 results were exact to double the precision

20 largest ulp errors (stored in a double)
   0.50000 ulp for sqrt(0.99999999999999989) = 0.99999999999999989)
   0.50000 ulp for sqrt(15.999999999999998) = 3.9999999999999996)
   0.50000 ulp for sqrt(0.015624999999999998) = 0.12499999999999999)
   0.50000 ulp for sqrt(0.24999999999999997) = 0.49999999999999994)
   0.50000 ulp for sqrt(63.999999999999993) = 7.9999999999999991)
   0.50000 ulp for sqrt(0.062499999999999993) = 0.24999999999999997)
   0.50000 ulp for sqrt(3.9999999999999996) = 1.9999999999999998)
   0.50000 ulp for sqrt(16.000000000000004) = 4)
   0.50000 ulp for sqrt(0.015625000000000003) = 0.125)
   0.50000 ulp for sqrt(4.0000000000000009) = 2)
   0.50000 ulp for sqrt(64.000000000000014) = 8)
   0.50000 ulp for sqrt(1.0000000000000002) = 1)
   0.50000 ulp for sqrt(0.25000000000000006) = 0.5)
   0.50000 ulp for sqrt(0.062500000000000014) = 0.25)
   0.50000 ulp for sqrt(2.538841562171981e-308) = 1.5933742693328462e-154)
   0.50000 ulp for sqrt(7.0503726185518891) = 2.655253776675949)
   0.50000 ulp for sqrt(9.5314451135632723) = 3.0873038583144474)
   0.50000 ulp for sqrt(491.05777431695867) = 22.159823427025735)
   0.50000 ulp for sqrt(0.37460865380155101) = 0.6120528194539675)
   0.50000 ulp for sqrt(3.2576094164239433e-308) = 1.8048848762245042e-154)

<tr><td align=left><a href=sqrt.res>sqrt</a></td><td align=right>1055</td><td align=right>0.50000</td><td>0.99999999999999989</td><td>0.99999999999999989</td></tr>