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);
}
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);
}
void
_acb_poly_mullow_transpose(acb_ptr res,
acb_srcptr poly1, slong len1,
acb_srcptr poly2, slong len2, slong n, slong prec)
{
arb_ptr a, b, c, d, e, f, w;
arb_ptr t;
slong i;
len1 = FLINT_MIN(len1, n);
len2 = FLINT_MIN(len2, n);
w = flint_malloc(sizeof(arb_struct) * (2 * (len1 + len2 + n)));
a = w;
b = a + len1;
c = b + len1;
d = c + len2;
e = d + len2;
f = e + n;
/* (e+fi) = (a+bi)(c+di) = (ac - bd) + (ad + bc)i */
t = _arb_vec_init(n);
for (i = 0; i < len1; i++)
{
a[i] = *acb_realref(poly1 + i);
b[i] = *acb_imagref(poly1 + i);
}
for (i = 0; i < len2; i++)
{
c[i] = *acb_realref(poly2 + i);
d[i] = *acb_imagref(poly2 + i);
}
for (i = 0; i < n; i++)
{
e[i] = *acb_realref(res + i);
f[i] = *acb_imagref(res + i);
}
_arb_poly_mullow(e, a, len1, c, len2, n, prec);
_arb_poly_mullow(t, b, len1, d, len2, n, prec);
_arb_vec_sub(e, e, t, n, prec);
_arb_poly_mullow(f, a, len1, d, len2, n, prec);
/* squaring */
if (poly1 == poly2 && len1 == len2)
{
_arb_vec_scalar_mul_2exp_si(f, f, n, 1);
}
else
{
_arb_poly_mullow(t, b, len1, c, len2, n, prec);
_arb_vec_add(f, f, t, n, prec);
}
for (i = 0; i < n; i++)
{
*acb_realref(res + i) = e[i];
*acb_imagref(res + i) = f[i];
}
_arb_vec_clear(t, n);
flint_free(w);
}
