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I have the following code

ord = 2;
Roo = AsymptoticSolve[h - q^3 (q - 2) == 0, q, {h, 0, ord}];
aexp = Roo[[4]][[1]][[2]];
bexp = Roo[[2]][[1]][[2]];
cexp = Roo[[1]][[1]][[2]];
dexp = Roo[[3]][[1]][[2]];
b1exp = Re[ComplexExpand[cexp]] // Simplify;
a12exp = Im[ComplexExpand[cexp]]^2 // Simplify;
A2exp = Assuming[h > 0, 
    Series[(aexp - b1exp)^2 + a12exp, {h, 0, ord}]] // Simplify;
B2exp = Assuming[h > 0, 
    Series[(bexp - b1exp)^2 + a12exp, {h, 0, ord}]] // Simplify;
gexp = Series[1/Sqrt[Sqrt[A2exp*B2exp]], {h, 0, ord}];
k2exp = Series[((aexp - bexp)^2 - (Sqrt[A2exp] - 
         Sqrt[B2exp])^2)/(4 Sqrt[A2exp*B2exp]), {h, 0, ord}];
y0 = Series[
   Solve[q^3 (q - 2) - (h - (1/\[Epsilon])^2) == 0, 
       q][[3]][[1]][[2]], {h, 0, 2}, 
   Assumptions -> \[Epsilon] != 0] /. {\[Epsilon] -> 10};
ExpCos\[Phi] = 
  Series[((aexp - Normal[y0])*Sqrt[B2exp] - (Normal[y0] - bexp)*
       Sqrt[A2exp])/((aexp - Normal[y0])*
       Sqrt[B2exp] + (Normal[y0] - bexp)*Sqrt[A2exp]), {h, 0, 1}];
Exp\[Phi] = 
  Pi + Assuming[h > 0, 
    Series[ArcTan[
      Sqrt[(1 - (Normal[ExpCos\[Phi]])^2)]/(Normal[
         ExpCos\[Phi]])], {h, 0, 1}]];
Collect[Normal[
  Assuming[h > 0, 
   Series[Normal[gexp]*
     Normal[Series[EllipticF[Exp\[Phi], k2exp], {h, 0, ord}]], {h, 0, 
     1}]]], h]

The goal is to obtain the final series expansion, so I can analyze it. The problem is the series expansion Exp\[Phi] does not finish running, at least after a couple of hours. I am wondering if there is anything I can do to optimize my code, and to actually make this finish running? In case anyone is interested, this is related to the series expansion of incomplete elliptic integrals of first kind.

Thanks in advance.

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1 Answer 1

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Here my approach to evaluate Exp\[Phi]

noExpCos\[Phi] = Normal[ExpCos\[Phi]] /. 0. -> 0;
Exp\[Phi] =Pi + Asymptotic[ArcTan[Sqrt[(1 - (noExpCos\[Phi] )^2)]/(noExpCos\[Phi] )],h -> 0] // Simplify

enter image description here

Your last codeline followas to

Normal[gexp] Asymptotic[EllipticF[Exp\[Phi], k2exp], h -> 0] //Collect[#, h] &

Hope it helps!

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  • $\begingroup$ Thanks, using that the following command also runs. $\endgroup$ Commented Sep 8, 2025 at 15:54
  • $\begingroup$ You are welcome! $\endgroup$ Commented Sep 8, 2025 at 15:54

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