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青青子衿
Posted at 2025-3-24 21:40:26
Last edited by 青青子衿 at 2025-4-1 14:23:54
\begin{align*}
&\int_{u}^{+\infty}\frac{\mathrm{d}t}{\left(t^{2}-\omega^{2}\right)\sqrt{(t^{2}-\chi)^{2}+\psi^{2}}}
+\int_{v}^{+\infty}\frac{\mathrm{d}t}{\left(t^{2}-\omega^{2}\right)\sqrt{(t^{2}-\chi)^{2}+\psi^{2}}}\\
&\qquad=\int_{w}^{+\infty}\frac{\mathrm{d}t}{\left(t^{2}-\omega^{2}\right)\sqrt{(t^{2}-\chi)^{2}+\psi^{2}}}\\
&\qquad\qquad+\tfrac{1}{4\omega\sqrt{(\omega^{2}-\chi)^{2}+\psi^{2}}}\operatorname{arctanh}\left(\tfrac{2u\omega\sqrt{((\omega^{2}-\chi)^{2}+\psi^{2})((u^{2}-\chi)^{2}+\psi^{2})}}{u^{2}\left((\omega^{2}-\chi)^{2}+\psi^{2}\right)+\omega^{2}\left((u^{2}-\chi)^{2}+\psi^{2}\right)}\right)\\
&\qquad\qquad\qquad+\tfrac{1}{4\omega\sqrt{(\omega^{2}-\chi)^{2}+\psi^{2}}}\operatorname{arctanh}\left(\tfrac{2v\omega\sqrt{((\omega^{2}-\chi)^{2}+\psi^{2})((v^{2}-\chi)^{2}+\psi^{2})}}{v^{2}\left((\omega^{2}-\chi)^{2}+\psi^{2}\right)+\omega^{2}\left((v^{2}-\chi)^{2}+\psi^{2}\right)}\right)\\
&\qquad\qquad-\tfrac{1}{4\omega\sqrt{(\omega^{2}-\chi)^{2}+\psi^{2}}}\operatorname{arctanh}\left(\tfrac{2w\omega\sqrt{((\omega^{2}-\chi)^{2}+\psi^{2})((w^{2}-\chi)^{2}+\psi^{2})}}{w^{2}\left((\omega^{2}-\chi)^{2}+\psi^{2}\right)+\omega^{2}\left((w^{2}-\chi)^{2}+\psi^{2}\right)}\right)\\
&-\tfrac{1}{2\omega\sqrt{(\omega^{2}-\chi)^{2}+\psi^{2}}}\operatorname{arctanh}\left(\tfrac{\frac{4A(A^{2}-\omega^{4})}{\omega}\sqrt{(\omega^{2}-\chi)^{2}+\psi^{2}}uvw}{(A-\omega^{2})^{2}(A+u^{2})(A+v^{2})(A+w^{2})+(A+\omega^{2})^{2}(A-u^{2})(A-v^{2})(A-w^{2})}\right)\\
&\qquad\qquad=\frac{1}{2 \omega \sqrt{(\omega ^2-\chi )^2+\psi ^2}}
\ln \left(\tfrac{
\begin{vmatrix}
1 & u^2 & u \sqrt{(u^2-\chi)^2+\psi ^2} \\
1 & v^2 & v \sqrt{(v^2-\chi )^2+\psi ^2} \\
1 & \omega ^2 & -\omega \sqrt{(\omega ^2-\chi)^2+\psi ^2} \\
\end{vmatrix}
}{
\begin{vmatrix}
1 & u^2 & u \sqrt{(u^2-\chi)^2+\psi ^2} \\
1 & v^2 & v \sqrt{(v^2-\chi )^2+\psi ^2} \\
1 & \omega ^2 & \omega \sqrt{(\omega ^2-\chi)^2+\psi ^2} \\
\end{vmatrix}
}\right)\\
\\
&\qquad\qquad\left\{\begin{split}
w&=\frac{v\sqrt{(u^{2}-\chi)^{2}+\psi^{2}}-u\sqrt{(v^{2}-\chi)^{2}+\psi^{2}}}{u^{2}-v^{2}}\\
A&=\sqrt{\chi^{2}+\psi^{2}}\\
\operatorname{arctanh}(x)&=\operatorname{arctanh}\left(x^{\operatorname{sgn}(1-\left|x\right|)}\right)
\end{split}\right.
\end{align*}
- lis3 = {u -> 9, v -> 7, \[Chi] -> 3, \[Psi] -> 2, \[Omega] -> 1};
- N[NIntegrate[
- 1/((t^2 - \[Omega]^2) Sqrt[(t^2 - \[Chi])^2 + \[Psi]^2]) /.
- lis3, {t, u /. lis3, +Infinity}, WorkingPrecision -> 50]
- + NIntegrate[
- 1/((t^2 - \[Omega]^2) Sqrt[(t^2 - \[Chi])^2 + \[Psi]^2]) /.
- lis3, {t, v /. lis3, +Infinity}, WorkingPrecision -> 50]
- - NIntegrate[
- 1/((t^2 - \[Omega]^2) Sqrt[(t^2 - \[Chi])^2 + \[Psi]^2]) /.
- lis3, {t, (
- v Sqrt[(u^2 - \[Chi])^2 + \[Psi]^2] -
- u Sqrt[(v^2 - \[Chi])^2 + \[Psi]^2])/(u^2 - v^2) /.
- lis3, +Infinity}, WorkingPrecision -> 50], 40]
- N[1/(2 \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \[Psi]^2]) Log[Det[( {
- {1, u^2, u Sqrt[(u^2 - \[Chi])^2 + \[Psi]^2]},
- {1, v^2, v Sqrt[(v^2 - \[Chi])^2 + \[Psi]^2]},
- {1, \[Omega]^2, -\[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \
- \[Psi]^2]}
- } )]/Det[( {
- {1, u^2, u Sqrt[(u^2 - \[Chi])^2 + \[Psi]^2]},
- {1, v^2, v Sqrt[(v^2 - \[Chi])^2 + \[Psi]^2]},
- {1, \[Omega]^2, \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \
- \[Psi]^2]}
- } )]] /. lis3, 40]
- AarcTanh[x_] := ArcTanh[x^Sign[1 - Abs[x]]]
- N[(1/(4 \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \[Psi]^2])
- AarcTanh[(
- 2 u*\[Omega] Sqrt[((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) ((u^2 \
- - \[Chi])^2 + \[Psi]^2)])/(
- u^2 ((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) + \[Omega]^2 ((u^2 \
- - \[Chi])^2 + \[Psi]^2))]
- +
- 1/(4 \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \[Psi]^2])
- AarcTanh[(
- 2 v*\[Omega] Sqrt[((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) ((v^2 \
- - \[Chi])^2 + \[Psi]^2)])/(
- v^2 ((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) + \[Omega]^2 ((v^2 \
- - \[Chi])^2 + \[Psi]^2))]
- -
- 1/(4 \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \[Psi]^2])
- AarcTanh[(
- 2 w*\[Omega] Sqrt[((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) ((w^2 \
- - \[Chi])^2 + \[Psi]^2)])/(
- w^2 ((\[Omega]^2 - \[Chi])^2 + \[Psi]^2) + \[Omega]^2 ((w^2 \
- - \[Chi])^2 + \[Psi]^2))]
- -
- 1/(2 \[Omega] Sqrt[(\[Omega]^2 - \[Chi])^2 + \[Psi]^2])
- AarcTanh[((
- 4 A (A^2 - \[Omega]^4))/\[Omega] Sqrt[(\[Omega]^2 - \
- \[Chi])^2 + \[Psi]^2] u*v*
- w)/((A - \[Omega]^2)^2 (A + u^2) (A + v^2) (A +
- w^2) + (A + \[Omega]^2)^2 (A - u^2) (A - v^2) (A -
- w^2))]) /. {
- W -> -((u*V - v*U )/(u - v)) - (U - V )/(u - v) w} /. {
- w -> (
- v Sqrt[(u^2 - \[Chi])^2 + \[Psi]^2] -
- u Sqrt[(v^2 - \[Chi])^2 + \[Psi]^2])/(u^2 - v^2)} /. {
- U -> Sqrt[(u^2 - \[Chi])^2 + \[Psi]^2],
- V -> Sqrt[(v^2 - \[Chi])^2 + \[Psi]^2],
- A -> Sqrt[\[Chi]^2 + \[Psi]^2]} /. lis3, 40]
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- points = {{a, 0}, {p, P}, {q, Q}};
- poly = InterpolatingPolynomial[points,
- x] - (x - a) ((
- p^2 Q - q^2 P - a (p*Q - q*P))/((a - p) (a - q) (p - q)) - (
- a (P - Q) + (p*Q - q*P))/((a - p) (a - q) (p - q)) x) //
- Factor
- points = {{u, U}, {v, V}};
- poly = InterpolatingPolynomial[points,
- x] - ((u*V - v*U )/(u - v) + (U - V )/(u - v) x) // Factor
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