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elliptic_roots, modular_eisenstein: detect real output

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This commit is contained in:
Fredrik Johansson 2017-02-17 06:47:10 +01:00
parent 01472aed72
commit 7711297f62
2 changed files with 42 additions and 0 deletions
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25
acb_elliptic/roots.c
View file

@ -16,12 +16,28 @@ void
acb_elliptic_roots(acb_t e1, acb_t e2, acb_t e3, const acb_t tau, slong prec) acb_elliptic_roots(acb_t e1, acb_t e2, acb_t e3, const acb_t tau, slong prec)
{ {
acb_t t1, t2, t3, t4; acb_t t1, t2, t3, t4;
int e1r, e23r;
if (!arb_is_positive(acb_imagref(tau)) || !arb_is_finite(acb_realref(tau)))
{
acb_indeterminate(e1);
acb_indeterminate(e2);
acb_indeterminate(e3);
return;
}
acb_init(t1); acb_init(t1);
acb_init(t2); acb_init(t2);
acb_init(t3); acb_init(t3);
acb_init(t4); acb_init(t4);
e1r = e23r = 0;
if (arb_is_int(acb_realref(tau)))
e1r = e23r = 1;
else if (arb_is_int_2exp_si(acb_realref(tau), -1))
e1r = 1;
acb_modular_theta(t1, t2, t3, t4, t1, tau, prec); acb_modular_theta(t1, t2, t3, t4, t1, tau, prec);
acb_pow_ui(t2, t2, 4, prec); acb_pow_ui(t2, t2, 4, prec);
@ -42,6 +58,15 @@ acb_elliptic_roots(acb_t e1, acb_t e2, acb_t e3, const acb_t tau, slong prec)
acb_mul(e3, e3, t3, prec); acb_mul(e3, e3, t3, prec);
acb_neg(e3, e3); acb_neg(e3, e3);
if (e1r)
arb_zero(acb_imagref(e1));
if (e23r)
{
arb_zero(acb_imagref(e2));
arb_zero(acb_imagref(e3));
}
acb_clear(t1); acb_clear(t1);
acb_clear(t2); acb_clear(t2);
acb_clear(t3); acb_clear(t3);

17
acb_modular/eisenstein.c
View file

@ -18,10 +18,20 @@ acb_modular_eisenstein(acb_ptr r, const acb_t tau, slong len, slong prec)
arf_t one_minus_eps; arf_t one_minus_eps;
acb_t tau_prime, t1, t2, t3, t4, q; acb_t tau_prime, t1, t2, t3, t4, q;
slong m, n; slong m, n;
int real;
if (len < 1) if (len < 1)
return; return;
if (!arb_is_positive(acb_imagref(tau)) || !arb_is_finite(acb_realref(tau)))
{
_acb_vec_indeterminate(r, len);
return;
}
real = arb_is_int_2exp_si(acb_realref(tau), -1);
psl2z_init(g); psl2z_init(g);
arf_init(one_minus_eps); arf_init(one_minus_eps);
acb_init(tau_prime); acb_init(tau_prime);
@ -110,6 +120,13 @@ acb_modular_eisenstein(acb_ptr r, const acb_t tau, slong len, slong prec)
} }
} }
if (real)
{
arb_zero(acb_imagref(r));
if (len > 1)
arb_zero(acb_imagref(r + 1));
}
/* compute more coefficients using recurrence */ /* compute more coefficients using recurrence */
for (n = 4; n < len + 2; n++) for (n = 4; n < len + 2; n++)
{ {