int arf_add(arf_ptr z, arf_srcptr x, arf_srcptr y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn; mp_srcptr xptr, yptr; slong shift; if (arf_is_special(x) || arf_is_special(y)) { return arf_add_special(z, x, y, prec, rnd); } shift = _fmpz_sub_small(ARF_EXPREF(x), ARF_EXPREF(y)); if (shift < 0) { arf_srcptr __t; __t = x; x = y; y = __t; shift = -shift; } ARF_GET_MPN_READONLY(xptr, xn, x); ARF_GET_MPN_READONLY(yptr, yn, y); return _arf_add_mpn(z, xptr, xn, ARF_SGNBIT(x), ARF_EXPREF(x), yptr, yn, ARF_SGNBIT(y), shift, prec, rnd); }
int arf_set_round(arf_t y, const arf_t x, slong prec, arf_rnd_t rnd) { if (arf_is_special(x)) { arf_set(y, x); return 0; } else { int inexact; slong fix; mp_size_t xn; mp_srcptr xptr; if (y == x) { mp_ptr xtmp; TMP_INIT; ARF_GET_MPN_READONLY(xptr, xn, x); /* exact */ if (xn * FLINT_BITS <= prec) return 0; if ((xn - 1) * FLINT_BITS < prec) { /* exact */ if ((xptr[0] << (prec - (xn-1) * FLINT_BITS)) == 0) return 0; } /* inexact */ TMP_START; xtmp = TMP_ALLOC(xn * sizeof(mp_limb_t)); flint_mpn_copyi(xtmp, xptr, xn); inexact = _arf_set_round_mpn(y, &fix, xtmp, xn, ARF_SGNBIT(x), prec, rnd); _fmpz_add_fast(ARF_EXPREF(y), ARF_EXPREF(x), fix); TMP_END; return inexact; } else { ARF_GET_MPN_READONLY(xptr, xn, x); inexact = _arf_set_round_mpn(y, &fix, xptr, xn, ARF_SGNBIT(x), prec, rnd); _fmpz_add_fast(ARF_EXPREF(y), ARF_EXPREF(x), fix); return inexact; } } }
int arf_cmpabs(const arf_t x, const arf_t y) { int ec, mc; mp_size_t xn, yn; mp_srcptr xp, yp; if (arf_is_special(x) || arf_is_special(y)) { if (arf_equal(x, y)) return 0; if (arf_is_nan(x) || arf_is_nan(y)) return 0; if (arf_is_zero(x)) return -1; if (arf_is_zero(y)) return 1; if (arf_is_inf(x)) return arf_is_inf(y) ? 0 : 1; if (arf_is_inf(y)) return -1; return -1; } ec = fmpz_cmp(ARF_EXPREF(x), ARF_EXPREF(y)); if (ec != 0) return (ec < 0) ? -1 : 1; ARF_GET_MPN_READONLY(xp, xn, x); ARF_GET_MPN_READONLY(yp, yn, y); if (xn >= yn) mc = mpn_cmp(xp + xn - yn, yp, yn); else mc = mpn_cmp(xp, yp + yn - xn, xn); if (mc != 0) return (mc < 0) ? -1 : 1; if (xn != yn) return (xn < yn) ? -1 : 1; return 0; }
int arf_sub_si(arf_ptr z, arf_srcptr x, slong y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn; mp_srcptr xptr, yptr; mp_limb_t ytmp; int xsgnbit, ysgnbit; fmpz yexp; slong shift; if (y == 0) { return arf_set_round(z, x, prec, rnd); } else if (arf_is_special(x)) { if (arf_is_zero(x)) { arf_set_si(z, y); return arf_neg_round(z, z, prec, rnd); } else { arf_set(z, x); return 0; } } ysgnbit = (y < 0); if (ysgnbit) ytmp = -y; else ytmp = y; yptr = &ytmp; yn = 1; yexp = FLINT_BITS; ysgnbit ^= 1; shift = _fmpz_sub_small(ARF_EXPREF(x), &yexp); xsgnbit = ARF_SGNBIT(x); ARF_GET_MPN_READONLY(xptr, xn, x); if (shift >= 0) return _arf_add_mpn(z, xptr, xn, xsgnbit, ARF_EXPREF(x), yptr, yn, ysgnbit, shift, prec, rnd); else return _arf_add_mpn(z, yptr, yn, ysgnbit, &yexp, xptr, xn, xsgnbit, -shift, prec, rnd); }
int arf_sub(arf_ptr z, arf_srcptr x, arf_srcptr y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn; mp_srcptr xptr, yptr; slong shift; if (arf_is_special(x) || arf_is_special(y)) { return arf_sub_special(z, x, y, prec, rnd); } shift = _fmpz_sub_small(ARF_EXPREF(x), ARF_EXPREF(y)); ARF_GET_MPN_READONLY(xptr, xn, x); ARF_GET_MPN_READONLY(yptr, yn, y); if (shift >= 0) return _arf_add_mpn(z, xptr, xn, ARF_SGNBIT(x), ARF_EXPREF(x), yptr, yn, ARF_SGNBIT(y) ^ 1, shift, prec, rnd); else return _arf_add_mpn(z, yptr, yn, ARF_SGNBIT(y) ^ 1, ARF_EXPREF(y), xptr, xn, ARF_SGNBIT(x), -shift, prec, rnd); }
int arf_add_fmpz_2exp(arf_ptr z, arf_srcptr x, const fmpz_t y, const fmpz_t exp, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn; mp_srcptr xptr, yptr; mp_limb_t ytmp; int xsgnbit, ysgnbit, inexact; fmpz_t yexp; slong shift; if (fmpz_is_zero(y)) { return arf_set_round(z, x, prec, rnd); } else if (arf_is_special(x)) { if (arf_is_zero(x)) { inexact = arf_set_round_fmpz(z, y, prec, rnd); arf_mul_2exp_fmpz(z, z, exp); return inexact; } else { arf_set(z, x); return 0; } } FMPZ_GET_MPN_READONLY(ysgnbit, yn, yptr, ytmp, *y) fmpz_init(yexp); fmpz_add_ui(yexp, exp, yn * FLINT_BITS); shift = _fmpz_sub_small(ARF_EXPREF(x), yexp); xsgnbit = ARF_SGNBIT(x); ARF_GET_MPN_READONLY(xptr, xn, x); if (shift >= 0) inexact = _arf_add_mpn(z, xptr, xn, xsgnbit, ARF_EXPREF(x), yptr, yn, ysgnbit, shift, prec, rnd); else inexact = _arf_add_mpn(z, yptr, yn, ysgnbit, yexp, xptr, xn, xsgnbit, -shift, prec, rnd); fmpz_clear(yexp); return inexact; }
int arf_sub_fmpz(arf_ptr z, arf_srcptr x, const fmpz_t y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn; mp_srcptr xptr, yptr; mp_limb_t ytmp; int xsgnbit, ysgnbit; fmpz yexp; slong shift; if (fmpz_is_zero(y)) { return arf_set_round(z, x, prec, rnd); } else if (arf_is_special(x)) { if (arf_is_zero(x)) { arf_set_fmpz(z, y); return arf_neg_round(z, z, prec, rnd); } else { arf_set(z, x); return 0; } } FMPZ_GET_MPN_READONLY(ysgnbit, yn, yptr, ytmp, *y) yexp = yn * FLINT_BITS; shift = _fmpz_sub_small(ARF_EXPREF(x), &yexp); ysgnbit ^= 1; xsgnbit = ARF_SGNBIT(x); ARF_GET_MPN_READONLY(xptr, xn, x); if (shift >= 0) return _arf_add_mpn(z, xptr, xn, xsgnbit, ARF_EXPREF(x), yptr, yn, ysgnbit, shift, prec, rnd); else return _arf_add_mpn(z, yptr, yn, ysgnbit, &yexp, xptr, xn, xsgnbit, -shift, prec, rnd); }
/* requires x != 1 */ static void arf_log_via_mpfr(arf_t z, const arf_t x, slong prec, arf_rnd_t rnd) { mpfr_t xf, zf; mp_ptr zptr, tmp; mp_srcptr xptr; mp_size_t xn, zn, val; TMP_INIT; TMP_START; zn = (prec + FLINT_BITS - 1) / FLINT_BITS; tmp = TMP_ALLOC(zn * sizeof(mp_limb_t)); ARF_GET_MPN_READONLY(xptr, xn, x); xf->_mpfr_d = (mp_ptr) xptr; xf->_mpfr_prec = xn * FLINT_BITS; xf->_mpfr_sign = ARF_SGNBIT(x) ? -1 : 1; xf->_mpfr_exp = ARF_EXP(x); zf->_mpfr_d = tmp; zf->_mpfr_prec = prec; zf->_mpfr_sign = 1; zf->_mpfr_exp = 0; mpfr_set_emin(MPFR_EMIN_MIN); mpfr_set_emax(MPFR_EMAX_MAX); mpfr_log(zf, xf, arf_rnd_to_mpfr(rnd)); val = 0; while (tmp[val] == 0) val++; ARF_GET_MPN_WRITE(zptr, zn - val, z); flint_mpn_copyi(zptr, tmp + val, zn - val); if (zf->_mpfr_sign < 0) ARF_NEG(z); fmpz_set_si(ARF_EXPREF(z), zf->_mpfr_exp); TMP_END; }
void arf_get_fmpz(fmpz_t z, const arf_t x, arf_rnd_t rnd) { if (arf_is_special(x)) { if (arf_is_zero(x)) { fmpz_zero(z); } else { flint_printf("arf_get_fmpz: cannot convert infinity or nan to integer\n"); abort(); } } else if (COEFF_IS_MPZ(*ARF_EXPREF(x))) { /* tiny */ if (fmpz_sgn(ARF_EXPREF(x)) < 0) { int negative = ARF_SGNBIT(x); if (rnd == ARF_RND_NEAR || rnd == ARF_RND_DOWN || (rnd == ARF_RND_FLOOR && !negative) || (rnd == ARF_RND_CEIL && negative)) { fmpz_zero(z); } else { fmpz_set_si(z, negative ? -1 : 1); } } else { flint_printf("arf_get_fmpz: number too large to convert to integer\n"); abort(); } } else { slong exp; int negative, inexact; mp_size_t xn, zn; mp_srcptr xp; __mpz_struct * zz; /* TBD: implement efficiently */ if (rnd == ARF_RND_NEAR) { fmpr_t t; fmpr_init(t); arf_get_fmpr(t, x); fmpr_get_fmpz(z, t, rnd); fmpr_clear(t); return; } exp = ARF_EXP(x); negative = ARF_SGNBIT(x); /* |x| < 1 */ if (exp <= 0) { if (rnd == ARF_RND_DOWN || (rnd == ARF_RND_FLOOR && !negative) || (rnd == ARF_RND_CEIL && negative)) { fmpz_zero(z); } else { fmpz_set_si(z, negative ? -1 : 1); } return; } ARF_GET_MPN_READONLY(xp, xn, x); /* |x| < 2^31 or 2^63 (must save 1 bit for rounding up!) */ if (exp < FLINT_BITS) { mp_limb_t v, v2; v = xp[xn - 1]; v2 = v >> (FLINT_BITS - exp); inexact = (xn > 1) || ((v2 << (FLINT_BITS - exp)) != v); if (inexact && rnd != ARF_RND_DOWN) { if (negative && (rnd == ARF_RND_UP || rnd == ARF_RND_FLOOR)) v2++; if (!negative && (rnd == ARF_RND_UP || rnd == ARF_RND_CEIL)) v2++; } if (negative) fmpz_neg_ui(z, v2); else fmpz_set_ui(z, v2); return; } /* |x| >= 1 */ zn = (exp + FLINT_BITS - 1) / FLINT_BITS; zz = _fmpz_promote(z); if (zz->_mp_alloc < zn) mpz_realloc2(zz, zn * FLINT_BITS); inexact = _arf_get_integer_mpn(zz->_mp_d, xp, xn, exp); zz->_mp_size = negative ? -zn : zn; _fmpz_demote_val(z); if (inexact && rnd != ARF_RND_DOWN) { if (negative && (rnd == ARF_RND_UP || rnd == ARF_RND_FLOOR)) fmpz_sub_ui(z, z, 1); if (!negative && (rnd == ARF_RND_UP || rnd == ARF_RND_CEIL)) fmpz_add_ui(z, z, 1); } }
int arf_submul_mpz(arf_ptr z, arf_srcptr x, const mpz_t y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn, zn, tn, alloc; mp_srcptr xptr, yptr, zptr; mp_ptr tptr, tptr2; fmpz_t texp, yexp; slong shift; int tsgnbit, ysgnbit, inexact; ARF_MUL_TMP_DECL yn = FLINT_ABS(y->_mp_size); if (arf_is_special(x) || yn == 0 || arf_is_special(z)) { if (arf_is_zero(z)) { /* TODO: make more efficient */ arf_mul_mpz(z, x, y, ARF_PREC_EXACT, rnd); return arf_neg_round(z, z, prec, rnd); } else if (arf_is_finite(x)) { return arf_set_round(z, z, prec, rnd); } else { /* todo: speed up */ arf_t t; arf_init(t); arf_mul_mpz(t, x, y, ARF_PREC_EXACT, ARF_RND_DOWN); inexact = arf_sub(z, z, t, prec, rnd); arf_clear(t); return inexact; } } ARF_GET_MPN_READONLY(xptr, xn, x); yptr = y->_mp_d; ysgnbit = (y->_mp_size > 0); *yexp = yn * FLINT_BITS; ARF_GET_MPN_READONLY(zptr, zn, z); fmpz_init(texp); tsgnbit = ARF_SGNBIT(x) ^ ysgnbit; alloc = tn = xn + yn; ARF_MUL_TMP_ALLOC(tptr2, alloc) tptr = tptr2; ARF_MPN_MUL(tptr, xptr, xn, yptr, yn); shift = (tptr[tn - 1] == 0) * FLINT_BITS; tn -= (tptr[tn - 1] == 0); _fmpz_add2_fast(texp, ARF_EXPREF(x), yexp, -shift); shift = _fmpz_sub_small(ARF_EXPREF(z), texp); if (shift >= 0) inexact = _arf_add_mpn(z, zptr, zn, ARF_SGNBIT(z), ARF_EXPREF(z), tptr, tn, tsgnbit, shift, prec, rnd); else inexact = _arf_add_mpn(z, tptr, tn, tsgnbit, texp, zptr, zn, ARF_SGNBIT(z), -shift, prec, rnd); ARF_MUL_TMP_FREE(tptr2, alloc) fmpz_clear(texp); return inexact; }
int arf_submul(arf_ptr z, arf_srcptr x, arf_srcptr y, slong prec, arf_rnd_t rnd) { mp_size_t xn, yn, zn, tn, alloc; mp_srcptr xptr, yptr, zptr; mp_ptr tptr, tptr2; fmpz_t texp; slong shift; int tsgnbit, inexact; ARF_MUL_TMP_DECL if (arf_is_special(x) || arf_is_special(y) || arf_is_special(z)) { if (arf_is_zero(z)) { return arf_neg_mul(z, x, y, prec, rnd); } else if (arf_is_finite(x) && arf_is_finite(y)) { return arf_set_round(z, z, prec, rnd); } else { /* todo: speed up */ arf_t t; arf_init(t); arf_mul(t, x, y, ARF_PREC_EXACT, ARF_RND_DOWN); inexact = arf_sub(z, z, t, prec, rnd); arf_clear(t); return inexact; } } tsgnbit = ARF_SGNBIT(x) ^ ARF_SGNBIT(y) ^ 1; ARF_GET_MPN_READONLY(xptr, xn, x); ARF_GET_MPN_READONLY(yptr, yn, y); ARF_GET_MPN_READONLY(zptr, zn, z); fmpz_init(texp); _fmpz_add2_fast(texp, ARF_EXPREF(x), ARF_EXPREF(y), 0); shift = _fmpz_sub_small(ARF_EXPREF(z), texp); alloc = tn = xn + yn; ARF_MUL_TMP_ALLOC(tptr2, alloc) tptr = tptr2; ARF_MPN_MUL(tptr, xptr, xn, yptr, yn); tn -= (tptr[0] == 0); tptr += (tptr[0] == 0); if (shift >= 0) inexact = _arf_add_mpn(z, zptr, zn, ARF_SGNBIT(z), ARF_EXPREF(z), tptr, tn, tsgnbit, shift, prec, rnd); else inexact = _arf_add_mpn(z, tptr, tn, tsgnbit, texp, zptr, zn, ARF_SGNBIT(z), -shift, prec, rnd); ARF_MUL_TMP_FREE(tptr2, alloc) fmpz_clear(texp); return inexact; }
int arf_root(arf_ptr z, arf_srcptr x, ulong k, slong prec, arf_rnd_t rnd) { mp_size_t xn, zn, val; mp_srcptr xptr; mp_ptr tmp, zptr; mpfr_t xf, zf; fmpz_t q, r; int inexact; if (k == 0) { arf_nan(z); return 0; } if (k == 1) return arf_set_round(z, x, prec, rnd); if (k == 2) return arf_sqrt(z, x, prec, rnd); if (arf_is_special(x)) { if (arf_is_neg_inf(x)) arf_nan(z); else arf_set(z, x); return 0; } if (ARF_SGNBIT(x)) { arf_nan(z); return 0; } fmpz_init(q); fmpz_init(r); /* x = m * 2^e where e = qk + r */ /* x^(1/k) = (m * 2^(qk+r))^(1/k) */ /* x^(1/k) = (m * 2^r)^(1/k) * 2^q */ fmpz_set_ui(r, k); fmpz_fdiv_qr(q, r, ARF_EXPREF(x), r); ARF_GET_MPN_READONLY(xptr, xn, x); zn = (prec + FLINT_BITS - 1) / FLINT_BITS; zf->_mpfr_d = tmp = flint_malloc(zn * sizeof(mp_limb_t)); zf->_mpfr_prec = prec; zf->_mpfr_sign = 1; zf->_mpfr_exp = 0; xf->_mpfr_d = (mp_ptr) xptr; xf->_mpfr_prec = xn * FLINT_BITS; xf->_mpfr_sign = 1; xf->_mpfr_exp = fmpz_get_ui(r); inexact = mpfr_root(zf, xf, k, arf_rnd_to_mpfr(rnd)); inexact = (inexact != 0); val = 0; while (tmp[val] == 0) val++; ARF_GET_MPN_WRITE(zptr, zn - val, z); flint_mpn_copyi(zptr, tmp + val, zn - val); fmpz_add_si(ARF_EXPREF(z), q, zf->_mpfr_exp); flint_free(tmp); fmpz_clear(q); fmpz_clear(r); return inexact; }
int _arb_get_mpn_fixed_mod_log2(mp_ptr w, fmpz_t q, mp_limb_t * error, const arf_t x, mp_size_t wn) { mp_srcptr xp; mp_size_t xn; int negative; long exp; ARF_GET_MPN_READONLY(xp, xn, x); exp = ARF_EXP(x); negative = ARF_SGNBIT(x); if (exp <= -1) { /* todo: just zero top */ flint_mpn_zero(w, wn); *error = _arf_get_integer_mpn(w, xp, xn, exp + wn * FLINT_BITS); if (!negative) { fmpz_zero(q); } else { if (wn > ARB_LOG_TAB2_LIMBS) return 0; mpn_sub_n(w, arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - wn, w, wn); *error += 1; /* log(2) has 1 ulp error */ fmpz_set_si(q, -1); } return 1; /* success */ } else { mp_ptr qp, rp, np; mp_srcptr dp; mp_size_t qn, rn, nn, dn, tn, alloc; TMP_INIT; tn = ((exp + 2) + FLINT_BITS - 1) / FLINT_BITS; dn = wn + tn; /* denominator */ nn = wn + 2 * tn; /* numerator */ qn = nn - dn + 1; /* quotient */ rn = dn; /* remainder */ if (dn > ARB_LOG_TAB2_LIMBS) return 0; TMP_START; alloc = qn + rn + nn; qp = TMP_ALLOC_LIMBS(alloc); rp = qp + qn; np = rp + rn; dp = arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - dn; /* todo: prove that zeroing is unnecessary */ flint_mpn_zero(np, nn); _arf_get_integer_mpn(np, xp, xn, exp + dn * FLINT_BITS); mpn_tdiv_qr(qp, rp, 0, np, nn, dp, dn); if (!negative) { flint_mpn_copyi(w, rp + tn, wn); *error = 2; } else { if (mpn_add_1(qp, qp, qn, 1)) { /* I believe this cannot happen (should prove it) */ printf("mod log(2): unexpected carry\n"); abort(); } mpn_sub_n(w, dp + tn, rp + tn, wn); *error = 3; } /* read the exponent */ while (qn > 1 && qp[qn-1] == 0) qn--; if (qn == 1) { if (!negative) fmpz_set_ui(q, qp[0]); else fmpz_neg_ui(q, qp[0]); } else { fmpz_set_mpn_large(q, qp, qn, negative); } TMP_END; return 1; } }
void arb_atan_arf(arb_t z, const arf_t x, slong prec) { if (arf_is_special(x)) { if (arf_is_zero(x)) { arb_zero(z); } else if (arf_is_pos_inf(x)) { arb_const_pi(z, prec); arb_mul_2exp_si(z, z, -1); } else if (arf_is_neg_inf(x)) { arb_const_pi(z, prec); arb_mul_2exp_si(z, z, -1); arb_neg(z, z); } else { arb_indeterminate(z); } } else if (COEFF_IS_MPZ(*ARF_EXPREF(x))) { if (fmpz_sgn(ARF_EXPREF(x)) < 0) arb_atan_eps(z, x, prec); else arb_atan_inf_eps(z, x, prec); } else { slong exp, wp, wn, N, r; mp_srcptr xp; mp_size_t xn, tn; mp_ptr tmp, w, t, u; mp_limb_t p1, q1bits, p2, q2bits, error, error2; int negative, inexact, reciprocal; TMP_INIT; exp = ARF_EXP(x); negative = ARF_SGNBIT(x); if (exp < -(prec/2) - 2 || exp > prec + 2) { if (exp < 0) arb_atan_eps(z, x, prec); else arb_atan_inf_eps(z, x, prec); return; } ARF_GET_MPN_READONLY(xp, xn, x); /* Special case: +/- 1 (we require |x| != 1 later on) */ if (exp == 1 && xn == 1 && xp[xn-1] == LIMB_TOP) { arb_const_pi(z, prec); arb_mul_2exp_si(z, z, -2); if (negative) arb_neg(z, z); return; } /* Absolute working precision (NOT rounded to a limb multiple) */ wp = prec - FLINT_MIN(0, exp) + 4; /* Too high precision to use table */ if (wp > ARB_ATAN_TAB2_PREC) { arb_atan_arf_bb(z, x, prec); return; } /* Working precision in limbs */ wn = (wp + FLINT_BITS - 1) / FLINT_BITS; TMP_START; tmp = TMP_ALLOC_LIMBS(4 * wn + 3); w = tmp; /* requires wn+1 limbs */ t = w + wn + 1; /* requires wn+1 limbs */ u = t + wn + 1; /* requires 2wn+1 limbs */ /* ----------------------------------------------------------------- */ /* Convert x or 1/x to a fixed-point number |w| < 1 */ /* ----------------------------------------------------------------- */ if (exp <= 0) /* |x| < 1 */ { reciprocal = 0; /* todo: just zero top */ flint_mpn_zero(w, wn); /* w = x as a fixed-point number */ error = _arf_get_integer_mpn(w, xp, xn, exp + wn * FLINT_BITS); } else /* |x| > 1 */ { slong one_exp, one_limbs, one_bits; mp_ptr one; reciprocal = 1; one_exp = xn * FLINT_BITS + wn * FLINT_BITS - exp; flint_mpn_zero(w, wn); /* 1/x becomes zero */ if (one_exp >= FLINT_BITS - 1) { /* w = 1/x */ one_limbs = one_exp / FLINT_BITS; one_bits = one_exp % FLINT_BITS; if (one_limbs + 1 >= xn) { one = TMP_ALLOC_LIMBS(one_limbs + 1); flint_mpn_zero(one, one_limbs); one[one_limbs] = UWORD(1) << one_bits; /* todo: only zero necessary part */ flint_mpn_zero(w, wn); mpn_tdiv_q(w, one, one_limbs + 1, xp, xn); /* Now w must be < 1 since x > 1 and we rounded down; thus w[wn] must be zero */ } } /* todo: moderate powers of two would be exact... */ error = 1; } /* ----------------------------------------------------------------- */ /* Table-based argument reduction */ /* ----------------------------------------------------------------- */ /* choose p such that p/q <= x < (p+1)/q */ if (wp <= ARB_ATAN_TAB1_PREC) q1bits = ARB_ATAN_TAB1_BITS; else q1bits = ARB_ATAN_TAB21_BITS; p1 = w[wn-1] >> (FLINT_BITS - q1bits); /* atan(w) = atan(p/q) + atan(w2) */ /* where w2 = (q*w-p)/(q+p*w) */ if (p1 != 0) { t[wn] = (UWORD(1) << q1bits) + mpn_mul_1(t, w, wn, p1); flint_mpn_zero(u, wn); u[2 * wn] = mpn_lshift(u + wn, w, wn, q1bits) - p1; mpn_tdiv_q(w, u, 2 * wn + 1, t, wn + 1); error++; /* w2 is computed with 1 ulp error */ } /* Do a second round of argument reduction */ if (wp <= ARB_ATAN_TAB1_PREC) { p2 = 0; } else { q2bits = ARB_ATAN_TAB21_BITS + ARB_ATAN_TAB22_BITS; p2 = w[wn-1] >> (FLINT_BITS - q2bits); if (p2 != 0) { t[wn] = (UWORD(1) << q2bits) + mpn_mul_1(t, w, wn, p2); flint_mpn_zero(u, wn); u[2 * wn] = mpn_lshift(u + wn, w, wn, q2bits) - p2; mpn_tdiv_q(w, u, 2 * wn + 1, t, wn + 1); error++; } } /* |w| <= 2^-r */ r = _arb_mpn_leading_zeros(w, wn); /* N >= (wp-r)/(2r) */ N = (wp - r + (2*r-1)) / (2*r); /* Evaluate Taylor series */ _arb_atan_taylor_rs(t, &error2, w, wn, N, 1); /* Taylor series evaluation error */ error += error2; /* Size of output number */ tn = wn; /* First table lookup */ if (p1 != 0) { if (wp <= ARB_ATAN_TAB1_PREC) mpn_add_n(t, t, arb_atan_tab1[p1] + ARB_ATAN_TAB1_LIMBS - tn, tn); else mpn_add_n(t, t, arb_atan_tab21[p1] + ARB_ATAN_TAB2_LIMBS - tn, tn); error++; } /* Second table lookup */ if (p2 != 0) { mpn_add_n(t, t, arb_atan_tab22[p2] + ARB_ATAN_TAB2_LIMBS - tn, tn); error++; } /* pi/2 - atan(1/x) */ if (reciprocal) { t[tn] = LIMB_ONE - mpn_sub_n(t, arb_atan_pi2_minus_one + ARB_ATAN_TAB2_LIMBS - tn, t, tn); /* result can be >= 1 */ tn += (t[tn] != 0); /* error of pi/2 */ error++; } /* The accumulated arithmetic error */ mag_set_ui_2exp_si(arb_radref(z), error, -wn * FLINT_BITS); /* Truncation error from the Taylor series */ mag_add_ui_2exp_si(arb_radref(z), arb_radref(z), 1, -r*(2*N+1)); /* Set the midpoint */ inexact = _arf_set_mpn_fixed(arb_midref(z), t, tn, wn, negative, prec, ARB_RND); if (inexact) arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec); TMP_END; } }
void arb_log_arf(arb_t z, const arf_t x, slong prec) { if (arf_is_special(x)) { if (arf_is_pos_inf(x)) arb_pos_inf(z); else arb_indeterminate(z); } else if (ARF_SGNBIT(x)) { arb_indeterminate(z); } else if (ARF_IS_POW2(x)) { if (fmpz_is_one(ARF_EXPREF(x))) { arb_zero(z); } else { fmpz_t exp; fmpz_init(exp); _fmpz_add_fast(exp, ARF_EXPREF(x), -1); arb_const_log2(z, prec + 2); arb_mul_fmpz(z, z, exp, prec); fmpz_clear(exp); } } else if (COEFF_IS_MPZ(*ARF_EXPREF(x))) { arb_log_arf_huge(z, x, prec); } else { slong exp, wp, wn, N, r, closeness_to_one; mp_srcptr xp; mp_size_t xn, tn; mp_ptr tmp, w, t, u; mp_limb_t p1, q1bits, p2, q2bits, error, error2, cy; int negative, inexact, used_taylor_series; TMP_INIT; exp = ARF_EXP(x); negative = 0; ARF_GET_MPN_READONLY(xp, xn, x); /* compute a c >= 0 such that |x-1| <= 2^(-c) if c > 0 */ closeness_to_one = 0; if (exp == 0) { slong i; closeness_to_one = FLINT_BITS - FLINT_BIT_COUNT(~xp[xn - 1]); if (closeness_to_one == FLINT_BITS) { for (i = xn - 2; i > 0 && xp[i] == LIMB_ONES; i--) closeness_to_one += FLINT_BITS; closeness_to_one += (FLINT_BITS - FLINT_BIT_COUNT(~xp[i])); } } else if (exp == 1) { closeness_to_one = FLINT_BITS - FLINT_BIT_COUNT(xp[xn - 1] & (~LIMB_TOP)); if (closeness_to_one == FLINT_BITS) { slong i; for (i = xn - 2; xp[i] == 0; i--) closeness_to_one += FLINT_BITS; closeness_to_one += (FLINT_BITS - FLINT_BIT_COUNT(xp[i])); } closeness_to_one--; } /* if |t-1| <= 0.5 */ /* |log(1+t) - t| <= t^2 */ /* |log(1+t) - (t-t^2/2)| <= t^3 */ if (closeness_to_one > prec + 1) { inexact = arf_sub_ui(arb_midref(z), x, 1, prec, ARB_RND); mag_set_ui_2exp_si(arb_radref(z), 1, -2 * closeness_to_one); if (inexact) arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec); return; } else if (2 * closeness_to_one > prec + 1) { arf_t t, u; arf_init(t); arf_init(u); arf_sub_ui(t, x, 1, ARF_PREC_EXACT, ARF_RND_DOWN); arf_mul(u, t, t, ARF_PREC_EXACT, ARF_RND_DOWN); arf_mul_2exp_si(u, u, -1); inexact = arf_sub(arb_midref(z), t, u, prec, ARB_RND); mag_set_ui_2exp_si(arb_radref(z), 1, -3 * closeness_to_one); if (inexact) arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec); arf_clear(t); arf_clear(u); return; } /* Absolute working precision (NOT rounded to a limb multiple) */ wp = prec + closeness_to_one + 5; /* Too high precision to use table */ if (wp > ARB_LOG_TAB2_PREC) { arf_log_via_mpfr(arb_midref(z), x, prec, ARB_RND); arf_mag_set_ulp(arb_radref(z), arb_midref(z), prec); return; } /* Working precision in limbs */ wn = (wp + FLINT_BITS - 1) / FLINT_BITS; TMP_START; tmp = TMP_ALLOC_LIMBS(4 * wn + 3); w = tmp; /* requires wn+1 limbs */ t = w + wn + 1; /* requires wn+1 limbs */ u = t + wn + 1; /* requires 2wn+1 limbs */ /* read x-1 */ if (xn <= wn) { flint_mpn_zero(w, wn - xn); mpn_lshift(w + wn - xn, xp, xn, 1); error = 0; } else { mpn_lshift(w, xp + xn - wn, wn, 1); error = 1; } /* First table-based argument reduction */ if (wp <= ARB_LOG_TAB1_PREC) q1bits = ARB_LOG_TAB11_BITS; else q1bits = ARB_LOG_TAB21_BITS; p1 = w[wn-1] >> (FLINT_BITS - q1bits); /* Special case: covers logarithms of small integers */ if (xn == 1 && (w[wn-1] == (p1 << (FLINT_BITS - q1bits)))) { p2 = 0; flint_mpn_zero(t, wn); used_taylor_series = 0; N = r = 0; /* silence compiler warning */ } else { /* log(1+w) = log(1+p/q) + log(1 + (qw-p)/(p+q)) */ w[wn] = mpn_mul_1(w, w, wn, UWORD(1) << q1bits) - p1; mpn_divrem_1(w, 0, w, wn + 1, p1 + (UWORD(1) << q1bits)); error += 1; /* Second table-based argument reduction (fused with log->atanh conversion) */ if (wp <= ARB_LOG_TAB1_PREC) q2bits = ARB_LOG_TAB11_BITS + ARB_LOG_TAB12_BITS; else q2bits = ARB_LOG_TAB21_BITS + ARB_LOG_TAB22_BITS; p2 = w[wn-1] >> (FLINT_BITS - q2bits); u[2 * wn] = mpn_lshift(u + wn, w, wn, q2bits); flint_mpn_zero(u, wn); flint_mpn_copyi(t, u + wn, wn + 1); t[wn] += p2 + (UWORD(1) << (q2bits + 1)); u[2 * wn] -= p2; mpn_tdiv_q(w, u, 2 * wn + 1, t, wn + 1); /* propagated error from 1 ulp error: 2 atanh'(1/3) = 2.25 */ error += 3; /* |w| <= 2^-r */ r = _arb_mpn_leading_zeros(w, wn); /* N >= (wp-r)/(2r) */ N = (wp - r + (2*r-1)) / (2*r); N = FLINT_MAX(N, 0); /* Evaluate Taylor series */ _arb_atan_taylor_rs(t, &error2, w, wn, N, 0); /* Multiply by 2 */ mpn_lshift(t, t, wn, 1); /* Taylor series evaluation error (multiply by 2) */ error += error2 * 2; used_taylor_series = 1; } /* Size of output number */ tn = wn; /* First table lookup */ if (p1 != 0) { if (wp <= ARB_LOG_TAB1_PREC) mpn_add_n(t, t, arb_log_tab11[p1] + ARB_LOG_TAB1_LIMBS - tn, tn); else mpn_add_n(t, t, arb_log_tab21[p1] + ARB_LOG_TAB2_LIMBS - tn, tn); error++; } /* Second table lookup */ if (p2 != 0) { if (wp <= ARB_LOG_TAB1_PREC) mpn_add_n(t, t, arb_log_tab12[p2] + ARB_LOG_TAB1_LIMBS - tn, tn); else mpn_add_n(t, t, arb_log_tab22[p2] + ARB_LOG_TAB2_LIMBS - tn, tn); error++; } /* add exp * log(2) */ exp--; if (exp > 0) { cy = mpn_addmul_1(t, arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - tn, tn, exp); t[tn] = cy; tn += (cy != 0); error += exp; } else if (exp < 0) { t[tn] = 0; u[tn] = mpn_mul_1(u, arb_log_log2_tab + ARB_LOG_TAB2_LIMBS - tn, tn, -exp); if (mpn_cmp(t, u, tn + 1) >= 0) { mpn_sub_n(t, t, u, tn + 1); } else { mpn_sub_n(t, u, t, tn + 1); negative = 1; } error += (-exp); tn += (t[tn] != 0); } /* The accumulated arithmetic error */ mag_set_ui_2exp_si(arb_radref(z), error, -wn * FLINT_BITS); /* Truncation error from the Taylor series */ if (used_taylor_series) mag_add_ui_2exp_si(arb_radref(z), arb_radref(z), 1, -r*(2*N+1) + 1); /* Set the midpoint */ inexact = _arf_set_mpn_fixed(arb_midref(z), t, tn, wn, negative, prec); if (inexact) arf_mag_add_ulp(arb_radref(z), arb_radref(z), arb_midref(z), prec); TMP_END; } }