void
arb_poly_inv_series(arb_poly_t Qinv, const arb_poly_t Q, slong n, slong prec)
{
if (n == 0)
{
arb_poly_zero(Qinv);
return;
}
if (Q->length == 0)
{
arb_poly_fit_length(Qinv, n);
_arb_vec_indeterminate(Qinv->coeffs, n);
_arb_poly_set_length(Qinv, n);
return;
}
if (Qinv == Q)
{
arb_poly_t t;
arb_poly_init(t);
arb_poly_inv_series(t, Q, n, prec);
arb_poly_swap(Qinv, t);
arb_poly_clear(t);
return;
}
arb_poly_fit_length(Qinv, n);
_arb_poly_inv_series(Qinv->coeffs, Q->coeffs, Q->length, n, prec);
_arb_poly_set_length(Qinv, n);
_arb_poly_normalise(Qinv);
}
void
_arb_poly_log1p_series(arb_ptr res, arb_srcptr f, slong flen, slong n, slong prec)
{
arb_t a;
flen = FLINT_MIN(flen, n);
arb_init(a);
arb_log1p(a, f, prec);
if (flen == 1)
{
_arb_vec_zero(res + 1, n - 1);
}
else if (n == 2)
{
arb_add_ui(res, f + 0, 1, prec);
arb_div(res + 1, f + 1, res + 0, prec);
}
else if (_arb_vec_is_zero(f + 1, flen - 2)) /* f = a + bx^d */
{
slong i, j, d = flen - 1;
arb_add_ui(res, f + 0, 1, prec);
for (i = 1, j = d; j < n; j += d, i++)
{
if (i == 1)
arb_div(res + j, f + d, res, prec);
else
arb_mul(res + j, res + j - d, res + d, prec);
_arb_vec_zero(res + j - d + 1, flen - 2);
}
_arb_vec_zero(res + j - d + 1, n - (j - d + 1));
for (i = 2, j = 2 * d; j < n; j += d, i++)
arb_div_si(res + j, res + j, i % 2 ? i : -i, prec);
}
else
{
arb_ptr f_diff, f_inv;
slong alloc;
alloc = n + flen;
f_inv = _arb_vec_init(alloc);
f_diff = f_inv + n;
arb_add_ui(f_diff, f, 1, prec);
_arb_vec_set(f_diff + 1, f + 1, flen - 1);
_arb_poly_inv_series(f_inv, f_diff, flen, n, prec);
_arb_poly_derivative(f_diff, f, flen, prec);
_arb_poly_mullow(res, f_inv, n - 1, f_diff, flen - 1, n - 1, prec);
_arb_poly_integral(res, res, n, prec);
_arb_vec_clear(f_inv, alloc);
}
arb_swap(res, a);
arb_clear(a);
}
void
_arb_poly_revert_series_lagrange_fast(arb_ptr Qinv, arb_srcptr Q, long Qlen, long n, long prec)
{
long i, j, k, m;
arb_ptr R, S, T, tmp;
arb_t t;
if (n <= 2)
{
if (n >= 1)
arb_zero(Qinv);
if (n == 2)
arb_inv(Qinv + 1, Q + 1, prec);
return;
}
m = n_sqrt(n);
arb_init(t);
R = _arb_vec_init((n - 1) * m);
S = _arb_vec_init(n - 1);
T = _arb_vec_init(n - 1);
arb_zero(Qinv);
arb_inv(Qinv + 1, Q + 1, prec);
_arb_poly_inv_series(Ri(1), Q + 1, FLINT_MIN(Qlen, n) - 1, n - 1, prec);
for (i = 2; i <= m; i++)
_arb_poly_mullow(Ri(i), Ri((i + 1) / 2), n - 1, Ri(i / 2), n - 1, n - 1, prec);
for (i = 2; i < m; i++)
arb_div_ui(Qinv + i, Ri(i) + i - 1, i, prec);
_arb_vec_set(S, Ri(m), n - 1);
for (i = m; i < n; i += m)
{
arb_div_ui(Qinv + i, S + i - 1, i, prec);
for (j = 1; j < m && i + j < n; j++)
{
arb_mul(t, S + 0, Ri(j) + i + j - 1, prec);
for (k = 1; k <= i + j - 1; k++)
arb_addmul(t, S + k, Ri(j) + i + j - 1 - k, prec);
arb_div_ui(Qinv + i + j, t, i + j, prec);
}
if (i + 1 < n)
{
_arb_poly_mullow(T, S, n - 1, Ri(m), n - 1, n - 1, prec);
tmp = S; S = T; T = tmp;
}
}
arb_clear(t);
_arb_vec_clear(R, (n - 1) * m);
_arb_vec_clear(S, n - 1);
_arb_vec_clear(T, n - 1);
}
void
_arb_poly_sinh_cosh_series_exponential(arb_ptr s, arb_ptr c,
const arb_srcptr h, slong hlen, slong len, slong prec)
{
arb_ptr t, u, v;
arb_t s0, c0;
hlen = FLINT_MIN(hlen, len);
if (hlen == 1)
{
arb_sinh_cosh(s, c, h, prec);
_arb_vec_zero(s + 1, len - 1);
_arb_vec_zero(c + 1, len - 1);
return;
}
arb_init(s0);
arb_init(c0);
t = _arb_vec_init(3 * len);
u = t + len;
v = u + len;
arb_sinh_cosh(s0, c0, h, prec);
_arb_vec_set(t + 1, h + 1, hlen - 1);
_arb_poly_exp_series(t, t, len, len, prec);
/* todo: part of the inverse could be avoided since exp computes
it internally to half the length */
_arb_poly_inv_series(u, t, len, len, prec);
/* hyperbolic sine */
_arb_vec_sub(s, t, u, len, prec);
_arb_vec_scalar_mul_2exp_si(s, s, len, -1);
/* hyperbolic cosine */
_arb_vec_add(c, t, u, len, prec);
_arb_vec_scalar_mul_2exp_si(c, c, len, -1);
/* sinh(h0 + h1) = cosh(h0) sinh(h1) + sinh(h0) cosh(h1)
cosh(h0 + h1) = cosh(h0) cosh(h1) + sinh(h0) sinh(h1) */
if (!arb_is_zero(s0))
{
_arb_vec_scalar_mul(t, s, len, c0, prec);
_arb_vec_scalar_mul(u, c, len, s0, prec);
_arb_vec_scalar_mul(v, s, len, s0, prec);
_arb_vec_add(s, t, u, len, prec);
_arb_vec_scalar_mul(t, c, len, c0, prec);
_arb_vec_add(c, t, v, len, prec);
}
_arb_vec_clear(t, 3 * len);
arb_clear(s0);
arb_clear(c0);
}
int
sin_1x(arb_ptr out, const arb_t inp, void * params, long order, long prec)
{
arb_ptr x;
int xlen = FLINT_MIN(2, order);
x = _arb_vec_init(xlen);
arb_set(x, inp);
if (xlen > 1)
arb_one(x + 1);
_arb_poly_inv_series(out, x, xlen, order, prec);
_arb_poly_sin_series(out, out, order, order, prec);
_arb_vec_clear(x, xlen);
eval_count++;
return 0;
}
void
_arb_poly_div_series(arb_ptr Q, arb_srcptr A, long Alen,
arb_srcptr B, long Blen, long n, long prec)
{
Alen = FLINT_MIN(Alen, n);
Blen = FLINT_MIN(Blen, n);
if (Blen == 1)
{
_arb_vec_scalar_div(Q, A, Alen, B, prec);
_arb_vec_zero(Q + Alen, n - Alen);
}
else
{
arb_ptr Binv;
Binv = _arb_vec_init(n);
_arb_poly_inv_series(Binv, B, Blen, n, prec);
_arb_poly_mullow(Q, Binv, n, A, Alen, n, prec);
_arb_vec_clear(Binv, n);
}
}
void
_arb_poly_rgamma_series(arb_ptr res, arb_srcptr h, long hlen, long len, long prec)
{
int reflect;
long i, rflen, r, n, wp;
arb_ptr t, u, v;
arb_struct f[2];
hlen = FLINT_MIN(hlen, len);
wp = prec + FLINT_BIT_COUNT(prec);
t = _arb_vec_init(len);
u = _arb_vec_init(len);
v = _arb_vec_init(len);
arb_init(f);
arb_init(f + 1);
/* use zeta values at small integers */
if (arb_is_int(h) && (arf_cmpabs_ui(arb_midref(h), prec / 2) < 0))
{
r = arf_get_si(arb_midref(h), ARF_RND_DOWN);
_arb_poly_lgamma_series_at_one(u, len, wp);
_arb_vec_neg(u, u, len);
_arb_poly_exp_series(t, u, len, len, wp);
if (r == 1)
{
_arb_vec_swap(v, t, len);
}
else if (r <= 0)
{
arb_set(f, h);
arb_one(f + 1);
rflen = FLINT_MIN(len, 2 - r);
_arb_poly_rising_ui_series(u, f, FLINT_MIN(2, len), 1 - r, rflen, wp);
_arb_poly_mullow(v, t, len, u, rflen, len, wp);
}
else
{
arb_one(f);
arb_one(f + 1);
rflen = FLINT_MIN(len, r);
_arb_poly_rising_ui_series(v, f, FLINT_MIN(2, len), r - 1, rflen, wp);
/* TODO: use div_series? */
_arb_poly_inv_series(u, v, rflen, len, wp);
_arb_poly_mullow(v, t, len, u, len, len, wp);
}
}
else
{
/* otherwise use Stirling series */
arb_gamma_stirling_choose_param(&reflect, &r, &n, h, 1, 0, wp);
/* rgamma(h) = (gamma(1-h+r) sin(pi h)) / (rf(1-h, r) * pi), h = h0 + t*/
if (reflect)
{
/* u = gamma(r+1-h) */
arb_sub_ui(f, h, r + 1, wp);
arb_neg(f, f);
_arb_poly_gamma_stirling_eval(t, f, n, len, wp);
_arb_poly_exp_series(u, t, len, len, wp);
for (i = 1; i < len; i += 2)
arb_neg(u + i, u + i);
/* v = sin(pi x) */
arb_const_pi(f + 1, wp);
arb_mul(f, h, f + 1, wp);
_arb_poly_sin_series(v, f, 2, len, wp);
_arb_poly_mullow(t, u, len, v, len, len, wp);
/* rf(1-h,r) * pi */
if (r == 0)
{
arb_const_pi(u, wp);
_arb_vec_scalar_div(v, t, len, u, wp);
}
else
{
arb_sub_ui(f, h, 1, wp);
arb_neg(f, f);
arb_set_si(f + 1, -1);
rflen = FLINT_MIN(len, r + 1);
_arb_poly_rising_ui_series(v, f, FLINT_MIN(2, len), r, rflen, wp);
arb_const_pi(u, wp);
_arb_vec_scalar_mul(v, v, rflen, u, wp);
/* divide by rising factorial */
/* TODO: might better to use div_series, when it has a good basecase */
_arb_poly_inv_series(u, v, rflen, len, wp);
_arb_poly_mullow(v, t, len, u, len, len, wp);
}
}
else
{
/* rgamma(h) = rgamma(h+r) rf(h,r) */
if (r == 0)
{
arb_add_ui(f, h, r, wp);
_arb_poly_gamma_stirling_eval(t, f, n, len, wp);
_arb_vec_neg(t, t, len);
_arb_poly_exp_series(v, t, len, len, wp);
}
else
{
arb_set(f, h);
arb_one(f + 1);
rflen = FLINT_MIN(len, r + 1);
_arb_poly_rising_ui_series(t, f, FLINT_MIN(2, len), r, rflen, wp);
arb_add_ui(f, h, r, wp);
_arb_poly_gamma_stirling_eval(v, f, n, len, wp);
_arb_vec_neg(v, v, len);
_arb_poly_exp_series(u, v, len, len, wp);
_arb_poly_mullow(v, u, len, t, rflen, len, wp);
}
}
}
/* compose with nonconstant part */
arb_zero(t);
_arb_vec_set(t + 1, h + 1, hlen - 1);
_arb_poly_compose_series(res, v, len, t, hlen, len, prec);
arb_clear(f);
arb_clear(f + 1);
_arb_vec_clear(t, len);
_arb_vec_clear(u, len);
_arb_vec_clear(v, len);
}
/* with inverse=1 simultaneously computes g = exp(-x) to length n
with inverse=0 uses g as scratch space, computing
g = exp(-x) only to length (n+1)/2 */
static void
_arb_poly_exp_series_newton(arb_ptr f, arb_ptr g,
arb_srcptr h, slong len, slong prec, int inverse, slong cutoff)
{
slong alloc;
arb_ptr T, U, hprime;
alloc = 3 * len;
T = _arb_vec_init(alloc);
U = T + len;
hprime = U + len;
_arb_poly_derivative(hprime, h, len, prec);
arb_zero(hprime + len - 1);
NEWTON_INIT(cutoff, len)
/* f := exp(h) + O(x^m), g := exp(-h) + O(x^m2) */
NEWTON_BASECASE(n)
_arb_poly_exp_series_basecase(f, h, n, n, prec);
_arb_poly_inv_series(g, f, (n + 1) / 2, (n + 1) / 2, prec);
NEWTON_END_BASECASE
/* extend from length m to length n */
NEWTON_LOOP(m, n)
slong m2 = (m + 1) / 2;
slong l = m - 1; /* shifted for derivative */
/* g := exp(-h) + O(x^m) */
_arb_poly_mullow(T, f, m, g, m2, m, prec);
_arb_poly_mullow(g + m2, g, m2, T + m2, m - m2, m - m2, prec);
_arb_vec_neg(g + m2, g + m2, m - m2);
/* U := h' + g (f' - f h') + O(x^(n-1))
Note: should replace h' by h' mod x^(m-1) */
_arb_vec_zero(f + m, n - m);
_arb_poly_mullow(T, f, n, hprime, n, n, prec); /* should be mulmid */
_arb_poly_derivative(U, f, n, prec);
arb_zero(U + n - 1); /* should skip low terms */
_arb_vec_sub(U + l, U + l, T + l, n - l, prec);
_arb_poly_mullow(T + l, g, n - m, U + l, n - m, n - m, prec);
_arb_vec_add(U + l, hprime + l, T + l, n - m, prec);
/* f := f + f * (h - int U) + O(x^n) = exp(h) + O(x^n) */
_arb_poly_integral(U, U, n, prec); /* should skip low terms */
_arb_vec_sub(U + m, h + m, U + m, n - m, prec);
_arb_poly_mullow(f + m, f, n - m, U + m, n - m, n - m, prec);
/* g := exp(-h) + O(x^n) */
/* not needed if we only want exp(x) */
if (n == len && inverse)
{
_arb_poly_mullow(T, f, n, g, m, n, prec);
_arb_poly_mullow(g + m, g, m, T + m, n - m, n - m, prec);
_arb_vec_neg(g + m, g + m, n - m);
}
NEWTON_END_LOOP
NEWTON_END
_arb_vec_clear(T, alloc);
}
void
_arb_poly_sin_cos_series_tangent(arb_ptr s, arb_ptr c,
arb_srcptr h, slong hlen, slong len, slong prec, int times_pi)
{
arb_ptr t, u, v;
arb_t s0, c0;
hlen = FLINT_MIN(hlen, len);
if (hlen == 1)
{
if (times_pi)
arb_sin_cos_pi(s, c, h, prec);
else
arb_sin_cos(s, c, h, prec);
_arb_vec_zero(s + 1, len - 1);
_arb_vec_zero(c + 1, len - 1);
return;
}
/*
sin(x) = 2*tan(x/2)/(1+tan(x/2)^2)
cos(x) = (1-tan(x/2)^2)/(1+tan(x/2)^2)
*/
arb_init(s0);
arb_init(c0);
t = _arb_vec_init(3 * len);
u = t + len;
v = u + len;
/* sin, cos of h0 */
if (times_pi)
arb_sin_cos_pi(s0, c0, h, prec);
else
arb_sin_cos(s0, c0, h, prec);
/* t = tan((h-h0)/2) */
arb_zero(u);
_arb_vec_scalar_mul_2exp_si(u + 1, h + 1, hlen - 1, -1);
if (times_pi)
{
arb_const_pi(t, prec);
_arb_vec_scalar_mul(u + 1, u + 1, hlen - 1, t, prec);
}
_arb_poly_tan_series(t, u, hlen, len, prec);
/* v = 1 + t^2 */
_arb_poly_mullow(v, t, len, t, len, len, prec);
arb_add_ui(v, v, 1, prec);
/* u = 1/(1+t^2) */
_arb_poly_inv_series(u, v, len, len, prec);
/* sine */
_arb_poly_mullow(s, t, len, u, len, len, prec);
_arb_vec_scalar_mul_2exp_si(s, s, len, 1);
/* cosine */
arb_sub_ui(v, v, 2, prec);
_arb_vec_neg(v, v, len);
_arb_poly_mullow(c, v, len, u, len, len, prec);
/* sin(h0 + h1) = cos(h0) sin(h1) + sin(h0) cos(h1)
cos(h0 + h1) = cos(h0) cos(h1) - sin(h0) sin(h1) */
if (!arb_is_zero(s0))
{
_arb_vec_scalar_mul(t, s, len, c0, prec);
_arb_vec_scalar_mul(u, c, len, s0, prec);
_arb_vec_scalar_mul(v, s, len, s0, prec);
_arb_vec_add(s, t, u, len, prec);
_arb_vec_scalar_mul(t, c, len, c0, prec);
_arb_vec_sub(c, t, v, len, prec);
}
_arb_vec_clear(t, 3 * len);
arb_clear(s0);
arb_clear(c0);
}
