def twinprime_fixed(prec):
def I(n):
return sum(
moebius(d) << (n // d) for d in xrange(1, n + 1) if not n % d) // n
wp = 2 * prec + 30
res = fone
primes = [from_rational(1, p, wp) for p in [2, 3, 5, 7]]
ppowers = [mpf_mul(p, p, wp) for p in primes]
n = 2
while 1:
a = mpf_zeta_int(n, wp)
for i in range(4):
a = mpf_mul(a, mpf_sub(fone, ppowers[i]), wp)
ppowers[i] = mpf_mul(ppowers[i], primes[i], wp)
a = mpf_pow_int(a, -I(n), wp)
if mpf_pos(a, prec + 10, 'n') == fone:
break
#from libmpf import to_str
#print n, to_str(mpf_sub(fone, a), 6)
res = mpf_mul(res, a, wp)
n += 1
res = mpf_mul(res, from_int(3 * 15 * 35), wp)
res = mpf_div(res, from_int(4 * 16 * 36), wp)
return to_fixed(res, prec)
def fraction(p, q):
"""Given Python integers p, q, return a lazy mpf with value p/q.
The value is updated with the precision.
>>> mp.dps = 15
>>> a = fraction(1,100)
>>> b = mpf(1)/100
>>> print a; print b
0.01
0.01
>>> mp.dps = 30
>>> print a; print b
0.01
0.0100000000000000002081668171172
>>> mp.dps = 15
"""
return constant(lambda prec, rnd: from_rational(p, q, prec, rnd),
'%s/%s' % (p, q))
def fraction(p, q):
"""
Given Python integers `(p, q)`, returns a lazy ``mpf`` representing
the fraction `p/q`. The value is updated with the precision.
>>> mp.dps = 15
>>> a = fraction(1,100)
>>> b = mpf(1)/100
>>> print a; print b
0.01
0.01
>>> mp.dps = 30
>>> print a; print b # a will be accurate
0.01
0.0100000000000000002081668171172
>>> mp.dps = 15
"""
return constant(lambda prec, rnd: from_rational(p, q, prec, rnd),
'%s/%s' % (p, q))
def twinprime_fixed(prec):
def I(n):
return sum(moebius(d)<<(n//d) for d in xrange(1,n+1) if not n%d)//n
wp = 2*prec + 30
res = fone
primes = [from_rational(1,p,wp) for p in [2,3,5,7]]
ppowers = [mpf_mul(p,p,wp) for p in primes]
n = 2
while 1:
a = mpf_zeta_int(n, wp)
for i in range(4):
a = mpf_mul(a, mpf_sub(fone, ppowers[i]), wp)
ppowers[i] = mpf_mul(ppowers[i], primes[i], wp)
a = mpf_pow_int(a, -I(n), wp)
if mpf_pos(a, prec+10, 'n') == fone:
break
#from libmpf import to_str
#print n, to_str(mpf_sub(fone, a), 6)
res = mpf_mul(res, a, wp)
n += 1
res = mpf_mul(res, from_int(3*15*35), wp)
res = mpf_div(res, from_int(4*16*36), wp)
return to_fixed(res, prec)
def mpf_bernoulli(n, prec, rnd=None):
"""Computation of Bernoulli numbers (numerically)"""
if n < 2:
if n < 0:
raise ValueError("Bernoulli numbers only defined for n >= 0")
if n == 0:
return fone
if n == 1:
return mpf_neg(fhalf)
# For odd n > 1, the Bernoulli numbers are zero
if n & 1:
return fzero
# If precision is extremely high, we can save time by computing
# the Bernoulli number at a lower precision that is sufficient to
# obtain the exact fraction, round to the exact fraction, and
# convert the fraction back to an mpf value at the original precision
if prec > BERNOULLI_PREC_CUTOFF and prec > bernoulli_size(n)*1.1 + 1000:
p, q = bernfrac(n)
return from_rational(p, q, prec, rnd or round_floor)
if n > MAX_BERNOULLI_CACHE:
return mpf_bernoulli_huge(n, prec, rnd)
wp = prec + 30
# Reuse nearby precisions
wp += 32 - (prec & 31)
cached = bernoulli_cache.get(wp)
if cached:
numbers, state = cached
if n in numbers:
if not rnd:
return numbers[n]
return mpf_pos(numbers[n], prec, rnd)
m, bin, bin1 = state
if n - m > 10:
return mpf_bernoulli_huge(n, prec, rnd)
else:
if n > 10:
return mpf_bernoulli_huge(n, prec, rnd)
numbers = {0:fone}
m, bin, bin1 = state = [2, MPZ(10), MPZ_ONE]
bernoulli_cache[wp] = (numbers, state)
while m <= n:
#print m
case = m % 6
# Accurately estimate size of B_m so we can use
# fixed point math without using too much precision
szbm = bernoulli_size(m)
s = 0
sexp = max(0, szbm) - wp
if m < 6:
a = MPZ_ZERO
else:
a = bin1
for j in xrange(1, m//6+1):
usign, uman, uexp, ubc = u = numbers[m-6*j]
if usign:
uman = -uman
s += lshift(a*uman, uexp-sexp)
# Update inner binomial coefficient
j6 = 6*j
a *= ((m-5-j6)*(m-4-j6)*(m-3-j6)*(m-2-j6)*(m-1-j6)*(m-j6))
a //= ((4+j6)*(5+j6)*(6+j6)*(7+j6)*(8+j6)*(9+j6))
if case == 0: b = mpf_rdiv_int(m+3, f3, wp)
if case == 2: b = mpf_rdiv_int(m+3, f3, wp)
if case == 4: b = mpf_rdiv_int(-m-3, f6, wp)
s = from_man_exp(s, sexp, wp)
b = mpf_div(mpf_sub(b, s, wp), from_int(bin), wp)
numbers[m] = b
m += 2
# Update outer binomial coefficient
bin = bin * ((m+2)*(m+3)) // (m*(m-1))
if m > 6:
bin1 = bin1 * ((2+m)*(3+m)) // ((m-7)*(m-6))
state[:] = [m, bin, bin1]
return numbers[n]
def _mpmath_(self, prec, rounding):
# XXX
return mp.make_mpf(from_rational(self[0], self[1], prec, rounding))
def mpf_cos_sin(x, prec, rnd=round_fast, which=0, pi=False):
"""
which:
0 -- return cos(x), sin(x)
1 -- return cos(x)
2 -- return sin(x)
3 -- return tan(x)
if pi=True, compute for pi*x
"""
sign, man, exp, bc = x
if not man:
if exp:
c, s = fnan, fnan
else:
c, s = fone, fzero
if which == 0: return c, s
if which == 1: return c
if which == 2: return s
if which == 3: return s
mag = bc + exp
wp = prec + 10
# Extremely small?
if mag < 0:
if mag < -wp:
if pi:
x = mpf_mul(x, mpf_pi(wp))
c = mpf_perturb(fone, 1, prec, rnd)
s = mpf_perturb(x, 1 - sign, prec, rnd)
if which == 0: return c, s
if which == 1: return c
if which == 2: return s
if which == 3: return mpf_perturb(x, sign, prec, rnd)
if pi:
if exp >= -1:
if exp == -1:
c = fzero
s = (fone, fnone)[bool(man & 2) ^ sign]
elif exp == 0:
c, s = (fnone, fzero)
else:
c, s = (fone, fzero)
if which == 0: return c, s
if which == 1: return c
if which == 2: return s
if which == 3: return mpf_div(s, c, prec, rnd)
# Subtract nearest half-integer (= mod by pi/2)
n = ((man >> (-exp - 2)) + 1) >> 1
man = man - (n << (-exp - 1))
mag2 = bitcount(man) + exp
wp = prec + 10 - mag2
offset = exp + wp
if offset >= 0:
t = man << offset
else:
t = man >> (-offset)
t = (t * pi_fixed(wp)) >> wp
else:
t, n, wp = mod_pi2(man, exp, mag, wp)
c, s = cos_sin_basecase(t, wp)
m = n & 3
if m == 1: c, s = -s, c
elif m == 2: c, s = -c, -s
elif m == 3: c, s = s, -c
if sign:
s = -s
if which == 0:
c = from_man_exp(c, -wp, prec, rnd)
s = from_man_exp(s, -wp, prec, rnd)
return c, s
if which == 1:
return from_man_exp(c, -wp, prec, rnd)
if which == 2:
return from_man_exp(s, -wp, prec, rnd)
if which == 3:
return from_rational(s, c, prec, rnd)
def mpf_expint(n, x, prec, rnd=round_fast, gamma=False):
"""
E_n(x), n an integer, x real
With gamma=True, computes Gamma(n,x) (upper incomplete gamma function)
Returns (real, None) if real, otherwise (real, imag)
The imaginary part is an optional branch cut term
"""
sign, man, exp, bc = x
if not man:
if gamma:
if x == fzero:
# Actually gamma function pole
if n <= 0:
return finf, None
return mpf_gamma_int(n, prec, rnd), None
if x == finf:
return fzero, None
# TODO: could return finite imaginary value at -inf
return fnan, fnan
else:
if x == fzero:
if n > 1:
return from_rational(1, n-1, prec, rnd), None
else:
return finf, None
if x == finf:
return fzero, None
return fnan, fnan
n_orig = n
if gamma:
n = 1-n
wp = prec + 20
xmag = exp + bc
# Beware of near-poles
if xmag < -10:
raise NotImplementedError
nmag = bitcount(abs(n))
have_imag = n > 0 and sign
negx = mpf_neg(x)
# Skip series if direct convergence
if n == 0 or 2*nmag - xmag < -wp:
if gamma:
v = mpf_exp(negx, wp)
re = mpf_mul(v, mpf_pow_int(x, n_orig-1, wp), prec, rnd)
else:
v = mpf_exp(negx, wp)
re = mpf_div(v, x, prec, rnd)
else:
# Finite number of terms, or...
can_use_asymptotic_series = -3*wp < n <= 0
# ...large enough?
if not can_use_asymptotic_series:
xi = abs(to_int(x))
m = min(max(1, xi-n), 2*wp)
siz = -n*nmag + (m+n)*bitcount(abs(m+n)) - m*xmag - (144*m//100)
tol = -wp-10
can_use_asymptotic_series = siz < tol
if can_use_asymptotic_series:
r = ((-MPZ_ONE) << (wp+wp)) // to_fixed(x, wp)
m = n
t = r*m
s = MPZ_ONE << wp
while m and t:
s += t
m += 1
t = (m*r*t) >> wp
v = mpf_exp(negx, wp)
if gamma:
# ~ exp(-x) * x^(n-1) * (1 + ...)
v = mpf_mul(v, mpf_pow_int(x, n_orig-1, wp), wp)
else:
# ~ exp(-x)/x * (1 + ...)
v = mpf_div(v, x, wp)
re = mpf_mul(v, from_man_exp(s, -wp), prec, rnd)
elif n == 1:
re = mpf_neg(mpf_ei(negx, prec, rnd))
elif n > 0 and n < 3*wp:
T1 = mpf_neg(mpf_ei(negx, wp))
if gamma:
if n_orig & 1:
T1 = mpf_neg(T1)
else:
T1 = mpf_mul(T1, mpf_pow_int(negx, n-1, wp), wp)
r = t = to_fixed(x, wp)
facs = [1] * (n-1)
for k in range(1,n-1):
facs[k] = facs[k-1] * k
facs = facs[::-1]
s = facs[0] << wp
for k in range(1, n-1):
if k & 1:
s -= facs[k] * t
else:
s += facs[k] * t
t = (t*r) >> wp
T2 = from_man_exp(s, -wp, wp)
T2 = mpf_mul(T2, mpf_exp(negx, wp))
if gamma:
T2 = mpf_mul(T2, mpf_pow_int(x, n_orig, wp), wp)
R = mpf_add(T1, T2)
re = mpf_div(R, from_int(ifac(n-1)), prec, rnd)
else:
raise NotImplementedError
if have_imag:
M = from_int(-ifac(n-1))
if gamma:
im = mpf_div(mpf_pi(wp), M, prec, rnd)
else:
im = mpf_div(mpf_mul(mpf_pi(wp), mpf_pow_int(negx, n_orig-1, wp), wp), M, prec, rnd)
return re, im
else:
return re, None
def mpf_bernoulli(n, prec, rnd=None):
"""Computation of Bernoulli numbers (numerically)"""
if n < 2:
if n < 0:
raise ValueError("Bernoulli numbers only defined for n >= 0")
if n == 0:
return fone
if n == 1:
return mpf_neg(fhalf)
# For odd n > 1, the Bernoulli numbers are zero
if n & 1:
return fzero
# If precision is extremely high, we can save time by computing
# the Bernoulli number at a lower precision that is sufficient to
# obtain the exact fraction, round to the exact fraction, and
# convert the fraction back to an mpf value at the original precision
if prec > BERNOULLI_PREC_CUTOFF and prec > bernoulli_size(n) * 1.1 + 1000:
p, q = bernfrac(n)
return from_rational(p, q, prec, rnd or round_floor)
if n > MAX_BERNOULLI_CACHE:
return mpf_bernoulli_huge(n, prec, rnd)
wp = prec + 30
# Reuse nearby precisions
wp += 32 - (prec & 31)
cached = bernoulli_cache.get(wp)
if cached:
numbers, state = cached
if n in numbers:
if not rnd:
return numbers[n]
return mpf_pos(numbers[n], prec, rnd)
m, bin, bin1 = state
if n - m > 10:
return mpf_bernoulli_huge(n, prec, rnd)
else:
if n > 10:
return mpf_bernoulli_huge(n, prec, rnd)
numbers = {0: fone}
m, bin, bin1 = state = [2, MP_BASE(10), MP_ONE]
bernoulli_cache[wp] = (numbers, state)
while m <= n:
#print m
case = m % 6
# Accurately estimate size of B_m so we can use
# fixed point math without using too much precision
szbm = bernoulli_size(m)
s = 0
sexp = max(0, szbm) - wp
if m < 6:
a = MP_ZERO
else:
a = bin1
for j in xrange(1, m // 6 + 1):
usign, uman, uexp, ubc = u = numbers[m - 6 * j]
if usign:
uman = -uman
s += lshift(a * uman, uexp - sexp)
# Update inner binomial coefficient
j6 = 6 * j
a *= ((m - 5 - j6) * (m - 4 - j6) * (m - 3 - j6) * (m - 2 - j6) *
(m - 1 - j6) * (m - j6))
a //= ((4 + j6) * (5 + j6) * (6 + j6) * (7 + j6) * (8 + j6) *
(9 + j6))
if case == 0: b = mpf_rdiv_int(m + 3, f3, wp)
if case == 2: b = mpf_rdiv_int(m + 3, f3, wp)
if case == 4: b = mpf_rdiv_int(-m - 3, f6, wp)
s = from_man_exp(s, sexp, wp)
b = mpf_div(mpf_sub(b, s, wp), from_int(bin), wp)
numbers[m] = b
m += 2
# Update outer binomial coefficient
bin = bin * ((m + 2) * (m + 3)) // (m * (m - 1))
if m > 6:
bin1 = bin1 * ((2 + m) * (3 + m)) // ((m - 7) * (m - 6))
state[:] = [m, bin, bin1]
def mpf_expint(n, x, prec, rnd=round_fast, gamma=False):
"""
E_n(x), n an integer, x real
With gamma=True, computes Gamma(n,x) (upper incomplete gamma function)
Returns (real, None) if real, otherwise (real, imag)
The imaginary part is an optional branch cut term
"""
sign, man, exp, bc = x
if not man:
if gamma:
if x == fzero:
# Actually gamma function pole
if n <= 0:
return finf
return mpf_gamma_int(n, prec, rnd)
if x == finf:
return fzero, None
# TODO: could return finite imaginary value at -inf
return fnan, fnan
else:
if x == fzero:
if n > 1:
return from_rational(1, n - 1, prec, rnd), None
else:
return finf, None
if x == finf:
return fzero, None
return fnan, fnan
n_orig = n
if gamma:
n = 1 - n
wp = prec + 20
xmag = exp + bc
# Beware of near-poles
if xmag < -10:
raise NotImplementedError
nmag = bitcount(abs(n))
have_imag = n > 0 and sign
negx = mpf_neg(x)
# Skip series if direct convergence
if n == 0 or 2 * nmag - xmag < -wp:
if gamma:
v = mpf_exp(negx, wp)
re = mpf_mul(v, mpf_pow_int(x, n_orig - 1, wp), prec, rnd)
else:
v = mpf_exp(negx, wp)
re = mpf_div(v, x, prec, rnd)
else:
# Finite number of terms, or...
can_use_asymptotic_series = -3 * wp < n <= 0
# ...large enough?
if not can_use_asymptotic_series:
xi = abs(to_int(x))
m = min(max(1, xi - n), 2 * wp)
siz = -n * nmag + (m + n) * bitcount(abs(m + n)) - m * xmag - (
144 * m // 100)
tol = -wp - 10
can_use_asymptotic_series = siz < tol
if can_use_asymptotic_series:
r = ((-MP_ONE) << (wp + wp)) // to_fixed(x, wp)
m = n
t = r * m
s = MP_ONE << wp
while m and t:
s += t
m += 1
t = (m * r * t) >> wp
v = mpf_exp(negx, wp)
if gamma:
# ~ exp(-x) * x^(n-1) * (1 + ...)
v = mpf_mul(v, mpf_pow_int(x, n_orig - 1, wp), wp)
else:
# ~ exp(-x)/x * (1 + ...)
v = mpf_div(v, x, wp)
re = mpf_mul(v, from_man_exp(s, -wp), prec, rnd)
elif n == 1:
re = mpf_neg(mpf_ei(negx, prec, rnd))
elif n > 0 and n < 3 * wp:
T1 = mpf_neg(mpf_ei(negx, wp))
if gamma:
if n_orig & 1:
T1 = mpf_neg(T1)
else:
T1 = mpf_mul(T1, mpf_pow_int(negx, n - 1, wp), wp)
r = t = to_fixed(x, wp)
facs = [1] * (n - 1)
for k in range(1, n - 1):
facs[k] = facs[k - 1] * k
facs = facs[::-1]
s = facs[0] << wp
for k in range(1, n - 1):
if k & 1:
s -= facs[k] * t
else:
s += facs[k] * t
t = (t * r) >> wp
T2 = from_man_exp(s, -wp, wp)
T2 = mpf_mul(T2, mpf_exp(negx, wp))
if gamma:
T2 = mpf_mul(T2, mpf_pow_int(x, n_orig, wp), wp)
R = mpf_add(T1, T2)
re = mpf_div(R, from_int(int_fac(n - 1)), prec, rnd)
else:
raise NotImplementedError
if have_imag:
M = from_int(-int_fac(n - 1))
if gamma:
im = mpf_div(mpf_pi(wp), M, prec, rnd)
else:
im = mpf_div(
mpf_mul(mpf_pi(wp), mpf_pow_int(negx, n_orig - 1, wp), wp), M,
prec, rnd)
return re, im
else:
return re, None
def mpf_cos_sin(x, prec, rnd=round_fast, which=0, pi=False):
"""
which:
0 -- return cos(x), sin(x)
1 -- return cos(x)
2 -- return sin(x)
3 -- return tan(x)
if pi=True, compute for pi*x
"""
sign, man, exp, bc = x
if not man:
if exp:
c, s = fnan, fnan
else:
c, s = fone, fzero
if which == 0:
return c, s
if which == 1:
return c
if which == 2:
return s
if which == 3:
return s
mag = bc + exp
wp = prec + 10
# Extremely small?
if mag < 0:
if mag < -wp:
if pi:
x = mpf_mul(x, mpf_pi(wp))
c = mpf_perturb(fone, 1, prec, rnd)
s = mpf_perturb(x, 1 - sign, prec, rnd)
if which == 0:
return c, s
if which == 1:
return c
if which == 2:
return s
if which == 3:
return mpf_perturb(x, sign, prec, rnd)
if pi:
if exp >= -1:
if exp == -1:
c = fzero
s = (fone, fnone)[bool(man & 2) ^ sign]
elif exp == 0:
c, s = (fnone, fzero)
else:
c, s = (fone, fzero)
if which == 0:
return c, s
if which == 1:
return c
if which == 2:
return s
if which == 3:
return mpf_div(s, c, prec, rnd)
# Subtract nearest half-integer (= mod by pi/2)
n = ((man >> (-exp - 2)) + 1) >> 1
man = man - (n << (-exp - 1))
mag2 = bitcount(man) + exp
wp = prec + 10 - mag2
offset = exp + wp
if offset >= 0:
t = man << offset
else:
t = man >> (-offset)
t = (t * pi_fixed(wp)) >> wp
else:
t, n, wp = mod_pi2(man, exp, mag, wp)
c, s = cos_sin_basecase(t, wp)
m = n & 3
if m == 1:
c, s = -s, c
elif m == 2:
c, s = -c, -s
elif m == 3:
c, s = s, -c
if sign:
s = -s
if which == 0:
c = from_man_exp(c, -wp, prec, rnd)
s = from_man_exp(s, -wp, prec, rnd)
return c, s
if which == 1:
return from_man_exp(c, -wp, prec, rnd)
if which == 2:
return from_man_exp(s, -wp, prec, rnd)
if which == 3:
return from_rational(s, c, prec, rnd)
def _mpmath_(self, prec, rounding):
# XXX
return mp.make_mpf(from_rational(self[0], self[1], prec, rounding))
