void
arb_addmul(arb_t z, const arb_t x, const arb_t y, slong prec)
{
mag_t zr, xm, ym;
int inexact;
if (arb_is_exact(y))
{
arb_addmul_arf(z, x, arb_midref(y), prec);
}
else if (arb_is_exact(x))
{
arb_addmul_arf(z, y, arb_midref(x), prec);
}
else if (ARB_IS_LAGOM(x) && ARB_IS_LAGOM(y) && ARB_IS_LAGOM(z))
{
mag_fast_init_set_arf(xm, arb_midref(x));
mag_fast_init_set_arf(ym, arb_midref(y));
mag_fast_init_set(zr, arb_radref(z));
mag_fast_addmul(zr, xm, arb_radref(y));
mag_fast_addmul(zr, ym, arb_radref(x));
mag_fast_addmul(zr, arb_radref(x), arb_radref(y));
inexact = arf_addmul(arb_midref(z), arb_midref(x), arb_midref(y),
prec, ARF_RND_DOWN);
if (inexact)
arf_mag_fast_add_ulp(zr, zr, arb_midref(z), prec);
*arb_radref(z) = *zr;
}
else
{
mag_init_set_arf(xm, arb_midref(x));
mag_init_set_arf(ym, arb_midref(y));
mag_init_set(zr, arb_radref(z));
mag_addmul(zr, xm, arb_radref(y));
mag_addmul(zr, ym, arb_radref(x));
mag_addmul(zr, arb_radref(x), arb_radref(y));
inexact = arf_addmul(arb_midref(z), arb_midref(x), arb_midref(y),
prec, ARF_RND_DOWN);
if (inexact)
arf_mag_add_ulp(arb_radref(z), zr, arb_midref(z), prec);
else
mag_set(arb_radref(z), zr);
mag_clear(zr);
mag_clear(xm);
mag_clear(ym);
}
}
/* check accuracy compared to reference algorithm */
void arb_exp_simple(arb_t res, const arb_t x, slong prec)
{
mag_t t, u;
mag_init_set(t, arb_radref(x));
mag_init(u);
arf_set(arb_midref(res), arb_midref(x));
mag_zero(arb_radref(res));
arb_exp(res, x, prec);
mag_expm1(t, t);
arb_get_mag(u, res);
mag_addmul(arb_radref(res), t, u);
mag_clear(t);
mag_clear(u);
}
void
mag_pow_ui_lower(mag_t z, const mag_t x, ulong e)
{
if (e <= 2)
{
if (e == 0)
mag_one(z);
else if (e == 1)
mag_set(z, x);
else
mag_mul_lower(z, x, x);
}
else if (mag_is_inf(x))
{
mag_inf(z);
}
else
{
mag_t y;
int i, bits;
mag_init_set(y, x);
bits = FLINT_BIT_COUNT(e);
for (i = bits - 2; i >= 0; i--)
{
mag_mul_lower(y, y, y);
if (e & (1UL << i))
mag_mul_lower(y, y, x);
}
mag_swap(z, y);
mag_clear(y);
}
}
void
_arb_sin_cos_generic(arb_t s, arb_t c, const arf_t x, const mag_t xrad, slong prec)
{
int want_sin, want_cos;
slong maglim;
want_sin = (s != NULL);
want_cos = (c != NULL);
if (arf_is_zero(x) && mag_is_zero(xrad))
{
if (want_sin) arb_zero(s);
if (want_cos) arb_one(c);
return;
}
if (!arf_is_finite(x) || !mag_is_finite(xrad))
{
if (arf_is_nan(x))
{
if (want_sin) arb_indeterminate(s);
if (want_cos) arb_indeterminate(c);
}
else
{
if (want_sin) arb_zero_pm_one(s);
if (want_cos) arb_zero_pm_one(c);
}
return;
}
maglim = FLINT_MAX(65536, 4 * prec);
if (mag_cmp_2exp_si(xrad, -16) > 0 || arf_cmpabs_2exp_si(x, maglim) > 0)
{
_arb_sin_cos_wide(s, c, x, xrad, prec);
return;
}
if (arf_cmpabs_2exp_si(x, -(prec/2) - 2) <= 0)
{
mag_t t, u, v;
mag_init(t);
mag_init(u);
mag_init(v);
arf_get_mag(t, x);
mag_add(t, t, xrad);
mag_mul(u, t, t);
/* |sin(z)-z| <= z^3/6 */
if (want_sin)
{
arf_set(arb_midref(s), x);
mag_set(arb_radref(s), xrad);
arb_set_round(s, s, prec);
mag_mul(v, u, t);
mag_div_ui(v, v, 6);
arb_add_error_mag(s, v);
}
/* |cos(z)-1| <= z^2/2 */
if (want_cos)
{
arf_one(arb_midref(c));
mag_mul_2exp_si(arb_radref(c), u, -1);
}
mag_clear(t);
mag_clear(u);
mag_clear(v);
return;
}
if (mag_is_zero(xrad))
{
arb_sin_cos_arf_generic(s, c, x, prec);
}
else
{
mag_t t;
slong exp, radexp;
mag_init_set(t, xrad);
exp = arf_abs_bound_lt_2exp_si(x);
radexp = MAG_EXP(xrad);
if (radexp < MAG_MIN_LAGOM_EXP || radexp > MAG_MAX_LAGOM_EXP)
radexp = MAG_MIN_LAGOM_EXP;
if (want_cos && exp < -2)
prec = FLINT_MIN(prec, 20 - FLINT_MAX(exp, radexp) - radexp);
else
prec = FLINT_MIN(prec, 20 - radexp);
arb_sin_cos_arf_generic(s, c, x, prec);
/* todo: could use quadratic bound */
if (want_sin) mag_add(arb_radref(s), arb_radref(s), t);
if (want_cos) mag_add(arb_radref(c), arb_radref(c), t);
mag_clear(t);
}
}
