úÎ Á µ?Order of the (truncated) approximation, which may be different 6 from the order of the fitted approximation, which is  length chebCoeffs - 1      estimates erfc(x) valid for 8 < x < 100 + This is based on index 5725 in Hart et al   "Error function related functions. The derivative of  is  x -> 2 / sqrt pi * exp (x^2),  and this uniquely determines  by  erf 0 = 0. Minimal complete definition is  or .  erfc x = 1 - erf x erfcx x = exp (x*x) * erfc x normcdf x = erfc(-x  sqrt 2)  2      erf-native-1.0.0.0Data.Number.Erf NR.Ch5.S8GSL.SpecFunc.ErfErferferfcerfcxnormcdf Chebyshev chebOrder chebCoeffschebAchebBchebEval chebEvalMerfferfcf erfserieserfc8 erfc8_sum