18 lines
817 B
Diff
18 lines
817 B
Diff
Source: https://pari.math.u-bordeaux.fr/cgi-bin/bugreport.cgi?att=1;bug=2441;filename=patch;msg=25
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See: https://pari.math.u-bordeaux.fr/cgi-bin/bugreport.cgi?bug=2441
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diff --git a/src/basemath/ellsea.c b/src/basemath/ellsea.c
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index a6871fa6a7..05f148eadd 100644
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--- a/src/basemath/ellsea.c
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+++ b/src/basemath/ellsea.c
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@@ -852,7 +852,8 @@ find_isogenous_from_Atkin(GEN a4, GEN a6, ulong ell, struct meqn *MEQN, GEN g, G
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GEN a4t, a6t, h;
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a4a6t(&a4t, &a6t, ell, E4t, E6t, T, p);
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h = find_kernel(a4, a6, ell, a4t, a6t, pp1, T, p, pp, e);
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- if (h) return gerepilecopy(ltop, mkvec3(a4t, a6t, h));
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+ if (h && signe(Fq_elldivpolmod(a4, a6, ell, h, T, pp))==0)
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+ return gerepilecopy(ltop, mkvec3(a4t, a6t, h));
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}
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}
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pari_err_BUG("find_isogenous_from_Atkin, kernel not found");
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