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authorDavid A. Madore <david+git@madore.org>2012-04-05 16:19:50 (GMT)
committerDavid A. Madore <david+git@madore.org>2012-04-05 16:19:50 (GMT)
commit88d0c083cfaeb70a62eda27b3e2850b9ece99110 (patch)
tree69d569b0c0d7f4c2ca60f0b75d5ee2f75e16da5c
parentd0f8d4a92d6eab284eb333d4e89f525c13295d12 (diff)
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[radicaux] Changement de base pour l'expression de cos(2π/19).
-rw-r--r--chapitres/radicaux.tex19
-rw-r--r--divers/sageries/racine-19e-de-14
2 files changed, 14 insertions, 9 deletions
diff --git a/chapitres/radicaux.tex b/chapitres/radicaux.tex
index 347ee24..9ce5f0a 100644
--- a/chapitres/radicaux.tex
+++ b/chapitres/radicaux.tex
@@ -1026,7 +1026,12 @@ Le calcul du sinus revient exactement à celui de $\beta_4 =
\subsubsection{$n=19$}\label{racine-19e-de-1} Nous ne donnons pas ici
les détails du calcul, qui sont extrêmement semblables au cas $n=13$.
Pour base du corps engendré par les racines $9$-ièmes (ou $18$-ièmes)
-de l'unité dans $\QQ$, on choisit : \XXX
+de l'unité dans $\QQ$, on choisit celle suggérée
+en \ref{racine-9e-de-1}, à savoir : $1$, $\sqrt{-3}$,
+$\root3\of{-\frac{1}{2} + \frac{1}{2}\sqrt{-3}}$,
+$\root3\of{-\frac{1}{2} - \frac{1}{2}\sqrt{-3}}$,
+$\root3\of{\frac{1}{2} + \frac{1}{2}\sqrt{-3}}$,
+$\root3\of{\frac{1}{2} - \frac{1}{2}\sqrt{-3}}$.
\begin{center}
\begin{tikzpicture}
@@ -1040,12 +1045,12 @@ $\footnotesize
(-1+\sqrt{-3})\,\root 3\of{7-3\,\sqrt{-3}}
+(-1-\sqrt{-3})\,\root 3\of{7+3\,\sqrt{-3}}\Big)
+\frac{1}{18}\,\root9\of{\frac{19}{2}} \times \\
-&\displaystyle \Bigg(\big(-\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}\big)\,\root 9\of{6865+7611\,\sqrt{-3}-22608\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-107316\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+63072\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}+16524\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\\
-&\displaystyle +\big(-\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}\big)\,\root 9\of{6865-7611\,\sqrt{-3}+81900\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+26964\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-10440\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}-18828\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\\
-&\displaystyle +\root 9\of{6865+7611\,\sqrt{-3}-4356\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+25416\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-44244\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}-6084\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\\
-&\displaystyle +\root 9\of{6865-7611\,\sqrt{-3}+25416\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-4356\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-6084\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}-44244\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\\
-&\displaystyle +\big(-\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}\big)\,\root 9\of{6865+7611\,\sqrt{-3}+26964\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+81900\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-18828\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}-10440\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\\
-&\displaystyle +\big(-\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}\big)\,\root 9\of{6865-7611\,\sqrt{-3}-107316\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-22608\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+16524\,\root 3\of{\frac{9}{2}+\frac{3}{2}\,\sqrt{-3}}+63072\,\root 3\of{\frac{9}{2}-\frac{3}{2}\,\sqrt{-3}}}\Bigg)
+&\displaystyle \Bigg(\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}\,\root 9\of{6865+7611\,\sqrt{-3}+63072\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+16524\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-6084\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-44244\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\\
+&\displaystyle +\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}\,\root 9\of{6865-7611\,\sqrt{-3}-10440\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-18828\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+63072\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+16524\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\\
+&\displaystyle +\root 9\of{6865+7611\,\sqrt{-3}-44244\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-6084\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-10440\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-18828\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\\
+&\displaystyle +\root 9\of{6865-7611\,\sqrt{-3}-6084\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-44244\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-18828\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-10440\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\\
+&\displaystyle +\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}\,\root 9\of{6865+7611\,\sqrt{-3}-18828\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-10440\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}+16524\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+63072\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\\
+&\displaystyle +\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}\,\root 9\of{6865-7611\,\sqrt{-3}+16524\,\root 3\of{-\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}+63072\,\root 3\of{-\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}-44244\,\root 3\of{\frac{1}{2}+\frac{1}{2}\,\sqrt{-3}}-6084\,\root 3\of{\frac{1}{2}-\frac{1}{2}\,\sqrt{-3}}}\Bigg)
\end{array}
$
};
diff --git a/divers/sageries/racine-19e-de-1 b/divers/sageries/racine-19e-de-1
index b9aa12c..35e6b07 100644
--- a/divers/sageries/racine-19e-de-1
+++ b/divers/sageries/racine-19e-de-1
@@ -6,13 +6,13 @@ powtab = [NN(18/gcd(i,18)) for i in range(18)]
atab = [alpha[i]^powtab[i] for i in range(18)]
atab_on_zeta_basis = [(QQ^6)((zeta.coordinates_in_terms_of_powers())(x)) for x in atab]
sqrtm3 = 2*zeta^3-1
-nice_basis = [1, sqrtm3, zeta, zeta^-1, -sqrtm3*zeta^5, sqrtm3*zeta^-5]
+nice_basis = [1, sqrtm3, zeta^2, zeta^-2, zeta, zeta^-1]
m = Matrix(QQ, 6, 6, [(QQ^6)((zeta.coordinates_in_terms_of_powers())(x)) for x in nice_basis])
atab_on_nice_basis = [v * m.inverse() for v in atab_on_zeta_basis]
zetab = [ZZ(floor(arg(CC(N(alpha[i])/N(atab[i]^(1/powtab[i]))))/arg(zeta)+0.5)) for i in range(18)]
btab = [zeta^zetab[i] for i in range(18)]
btab_on_zeta_basis = [(QQ^6)((zeta.coordinates_in_terms_of_powers())(x)) for x in btab]
btab_on_nice_basis = [v * m.inverse() for v in btab_on_zeta_basis]
-symbolic_basis = [1, sqrt(-3), ((1/2)*(1+sqrt(-3)))^(1/3), ((1/2)*(1-sqrt(-3)))^(1/3), ((1/2)*(9+3*sqrt(-3)))^(1/3), ((1/2)*(9-3*sqrt(-3)))^(1/3)]
+symbolic_basis = [1, sqrt(-3), ((1/2)*(-1+sqrt(-3)))^(1/3), ((1/2)*(-1-sqrt(-3)))^(1/3), ((1/2)*(1+sqrt(-3)))^(1/3), ((1/2)*(1-sqrt(-3)))^(1/3)]
symbolic_omega = sum([sum([btab_on_nice_basis[i][j]*symbolic_basis[j] for j in range(6)])*(sum([atab_on_nice_basis[i][j]*symbolic_basis[j] for j in range(6)]))^(1/powtab[i]) for i in range(18)])/18
symbolic_cos = sum([sum([btab_on_nice_basis[i][j]*symbolic_basis[j] for j in range(6)])*(sum([atab_on_nice_basis[i][j]*symbolic_basis[j] for j in range(6)]))^(1/powtab[i]) for i in range(0,18,2)])/18