■代数学の基本定理とiの1/2乗とガロア理論(その42)

 i=exp(iπ/2)・・・虚軸上の点

 i^i=exp(i^2π/2)=exp(−π/2)・・・実軸上の点

 i^i^i=exp(iπ/2)^exp(−π/2)

=exp(iπ/2exp(−π/2))

=cos{π/2exp(−π/2)}+isin{π/2exp(−π/2)}・・・単位円周上の点

 i^i^i^i=・・・

 i^i^i^i^i=・・・極限値はどのような1点に収束するのだろうか?

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i^ω=ω

この超越方程式は、

(-iπ/2・ω)exp(-iπ/2・ω)=-iπ/2

と書き直すことができて、ランベルトのW関数を用いて

i^i^i^i^i・・・=i2/π・W(-iπ/2)=0.4382829367+0.3605924719i

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 i^i^i=exp(iπ/2)^exp(−π/2)=cos{π/2exp(−π/2)}+isin{π/2exp(−π/2)}・・・単位円周上の点

において、r=1,t=π/2exp(−π/2)とおく.

 i^i^i^i=exp(iπ/2)^(rcost+irsint)=exp{-π/2rsint+iπ/2rcost}

=exp{-π/2rsint}{cos(cos(π/2rcost))+isin(cos(π/2rcost))}

R=exp{-π/2rsint},T=cos(π/2rcost)とおく。

 i^i^i^i^i=exp(iπ/2)^(RcosT+iRsinT)=exp{-π/2RsinT+iπ/2RcosT}

=exp{-π/2RsinT}{cos(cos(π/2RcosT))+isin(cos(π/2RcosT))}

調和散歩のようには表すことができない。

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 i=exp(iπ/2)=cos(π/2)+isin(π/2)

 i^i=exp(iπ/2)^exp(iπ/2)

 i^i=exp(iπ/2)^{cos(π/2)+isin(π/2)}

 i^i=exp(iπ/2{cos(π/2)+isin(π/2)})

 i^i=exp(-π/2sin(π/2)+iπ/2{cos(π/2)})

 i^i=exp(-π/2sin(π/2)){cosπ/2{cos(π/2)}+isin(π/2{cos(π/2)})}

 i^i=exp(−π/2)

 i^i^i=exp(iπ/2)^exp(−π/2)=exp(iπ/2exp(−π/2))

=cos{π/2exp(−π/2)}+isin{π/2exp(−π/2)}

r=1,t=π/2exp(−π/2)とおく.

 i^i^i^i=exp(iπ/2)^(rcost+irsint)=exp{-π/2rsint+iπ/2rcost}

=exp{-π/2rsint}{cos(cos(π/2rcost))+isin(cos(π/2rcost))}

R=exp{-π/2rsint},T=cos(π/2rcost)とおく。

 i^i^i^i^i=exp(iπ/2)^(RcosT+iRsinT)=exp{-π/2RsinT+iπ/2RcosT}

=exp{-π/2RsinT}{cos(cos(π/2RcosT))+isin(cos(π/2RcosT))}

U=exp{-π/2Rsint},V=cos(π/2RcosT)とおく。

 i^i^i^i^i^i=exp(iπ/2)^(UcosV+iUsinV)=exp{-π/2UsinV+iπ/2UcosV}

=exp{-π/2UsinV}{cos(cos(π/2UcosV))+isin(cos(π/2UcosV))}

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