result of erf is more precise than double 1205 out of 1277 times

0 errors <= 1% worse in accum, 0 <= 10%,2 <= 100%, 8 > 100%

3 results were exact to double the precision

20 largest ulp errors (from result in accumulator)
   0.10772 ulp for erf(0.225312055012176216) = 0.249999999999997974)
   0.10740 ulp for erf(0.22531205501207327) = 0.249999999999887562)
   0.10736 ulp for erf(0.225312055012163587) = 0.249999999999984429)
   0.10318 ulp for erf(-0.220614686665097565) = -0.244956651014343191)
   0.10316 ulp for erf(-0.220614686665073056) = -0.244956651014316851)
   0.10310 ulp for erf(-0.220614686664894144) = -0.24495665101412456)
   0.10309 ulp for erf(-0.220614686665097925) = -0.244956651014343579)
   0.10304 ulp for erf(-0.220614686665100895) = -0.244956651014346771)
   0.10303 ulp for erf(-0.220614686664715232) = -0.244956651013932269)
   0.09077 ulp for erf(0.476936276204469822) = 0.499999999999999944)
   0.09069 ulp for erf(0.476936276204463883) = 0.499999999999994615)
   0.09045 ulp for erf(0.476936276204468823) = 0.499999999999999056)
   0.08308 ulp for erf(-6.01265042607639533) = -1)
   0.08308 ulp for erf(-6.01265042610936362) = -1)
   0.08308 ulp for erf(-6.01265042610969314) = -1)
   0.08308 ulp for erf(-6.01265042610969669) = -1)
   0.06740 ulp for erf(0.183825489930200703) = 0.205111928999355708)
   0.06739 ulp for erf(0.183825489929979907) = 0.205111928999114845)
   0.06738 ulp for erf(0.183825489929759112) = 0.205111928998873982)
   0.06728 ulp for erf(0.183825489930311253) = 0.205111928999476306)

20 largest ulp errors (stored in a double)
   0.55029 ulp for erf(0.173003437415309991) = 0.19328324616993478)
   0.54396 ulp for erf(-0.489341802678973425) = -0.511083905768535796)
   0.54040 ulp for erf(-0.489341802678973925) = -0.51108390576853624)
   0.53615 ulp for erf(0.323079736607112478) = 0.352259768077648028)
   0.52689 ulp for erf(-0.237989233146952112) = -0.263557116890746901)
   0.52680 ulp for erf(0.183825489930278585) = 0.205111928999440668)
   0.52652 ulp for erf(-0.220614686665097565) = -0.244956651014343191)
   0.52554 ulp for erf(0.183825489930280112) = 0.205111928999442333)
   0.52414 ulp for erf(0.789433081039224605) = 0.735760585524578681)
   0.52372 ulp for erf(-0.237989233146952528) = -0.263557116890747345)
   0.51604 ulp for erf(-1.29245567966885266) = -0.932421680527195207)
   0.51470 ulp for erf(-0.11950033357842324) = -0.134202566094570735)
   0.51280 ulp for erf(1.33777652839433969) = 0.9414959220645438)
   0.51243 ulp for erf(0.644448162086819432) = 0.637908673562691209)
   0.50985 ulp for erf(1.29335219460623585) = 0.932611808380637064)
   0.50899 ulp for erf(-0.119500333578423115) = -0.134202566094570597)
   0.50814 ulp for erf(1.74973639081803101) = 0.986657752826208267)
   0.50762 ulp for erf(0.393287002759313054) = 0.421920264755931529)
   0.50749 ulp for erf(-1.2238890926331345) = -0.916519793341092348)
   0.50593 ulp for erf(1.17409017006009653) = 0.903168853005094308)

<tr><td align=left><a href=erf.res>erf</a></td><td align=right>1277</td><td align=right>0.55029</td><td>0.173003437415309991</td><td>0.19328324616993478</td></tr>