Function i2f_asympt 

fn i2f_asympt(x: f32) -> f32

Asymptotic expansion for I2.

Computes: sqrt(x) * exp(-x) * I2(x) = Pn(1/x)/Qn(1/x) hence: I2(x) = Pn(1/x)/Qm(1/x)*exp(x)/sqrt(x)

Generated by Mathematica:

<<FunctionApproximations`
ClearAll["Global`*"]
f[x_]:=Sqrt[x] Exp[-x] BesselI[2,x]
g[z_]:=f[1/z]
{err,approx}=MiniMaxApproximation[g[z],{z,{1/92.3,1/7.5},8,8},WorkingPrecision->70]
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}]]