Function k0ef_asympt 

fn k0ef_asympt(x: f32) -> f32

Generated in Wolfram

Computes sqrt(x)*exp(x)*K0(x)=Pn(1/x)/Qm(1/x) hence K0(x)exp(x) = Pn(1/x)/Qm(1/x) / sqrt(x)

<<FunctionApproximations`
ClearAll["Global`*"]
f[x_]:=Sqrt[x] Exp[x] BesselK[0,x]
g[z_]:=f[1/z]
{err,approx}=MiniMaxApproximation[g[z],{z,{2^-33,1},7,7},WorkingPrecision->60]
poly=Numerator[approx][[1]];
coeffs=CoefficientList[poly,z];
TableForm[Table[Row[{"'",NumberForm[coeffs[[i+1]],{50,50},ExponentFunction->(Null&)],"',"}],{i,0,Length[coeffs]-1}]]
poly=Denominator[approx][[1]];
coeffs=CoefficientList[poly,z];
TableForm[Table[Row[{"'",NumberForm[coeffs[[i+1]],{50,50},ExponentFunction->(Null&)],"',"}],{i,0,Length[coeffs]-1}]]