def add_terms(terms, prec, target_prec):
"""
Helper for evalf_add. Adds a list of (mpfval, accuracy) terms.
"""
if len(terms) == 1:
if not terms[0]:
# XXX: this is supposed to represent a scaled zero
return mpf_shift(fone, target_prec), -1
return terms[0]
max_extra_prec = 2*prec
sum_man, sum_exp, absolute_error = 0, 0, MINUS_INF
for x, accuracy in terms:
if not x:
continue
sign, man, exp, bc = x
if sign:
man = -man
absolute_error = max(absolute_error, bc+exp-accuracy)
delta = exp - sum_exp
if exp >= sum_exp:
# x much larger than existing sum?
# first: quick test
if (delta > max_extra_prec) and \
((not sum_man) or delta-bitcount(abs(sum_man)) > max_extra_prec):
sum_man = man
sum_exp = exp
else:
sum_man += (man << delta)
else:
delta = -delta
# x much smaller than existing sum?
if delta-bc > max_extra_prec:
if not sum_man:
sum_man, sum_exp = man, exp
else:
sum_man = (sum_man << delta) + man
sum_exp = exp
if absolute_error == MINUS_INF:
return None, None
if not sum_man:
# XXX: this is supposed to represent a scaled zero
return mpf_shift(fone, absolute_error), -1
if sum_man < 0:
sum_sign = 1
sum_man = -sum_man
else:
sum_sign = 0
sum_bc = bitcount(sum_man)
sum_accuracy = sum_exp + sum_bc - absolute_error
r = normalize(sum_sign, sum_man, sum_exp, sum_bc, target_prec,
round_nearest), sum_accuracy
#print "returning", to_str(r[0],50), r[1]
return r
def add_terms(terms, prec, target_prec):
"""
Helper for evalf_add. Adds a list of (mpfval, accuracy) terms.
"""
if len(terms) == 1:
if not terms[0]:
# XXX: this is supposed to represent a scaled zero
return mpf_shift(fone, target_prec), -1
return terms[0]
max_extra_prec = 2 * prec
sum_man, sum_exp, absolute_error = 0, 0, MINUS_INF
for x, accuracy in terms:
if not x:
continue
sign, man, exp, bc = x
if sign:
man = -man
absolute_error = max(absolute_error, bc + exp - accuracy)
delta = exp - sum_exp
if exp >= sum_exp:
# x much larger than existing sum?
# first: quick test
if (delta > max_extra_prec) and \
((not sum_man) or delta-bitcount(abs(sum_man)) > max_extra_prec):
sum_man = man
sum_exp = exp
else:
sum_man += (man << delta)
else:
delta = -delta
# x much smaller than existing sum?
if delta - bc > max_extra_prec:
if not sum_man:
sum_man, sum_exp = man, exp
else:
sum_man = (sum_man << delta) + man
sum_exp = exp
if absolute_error == MINUS_INF:
return None, None
if not sum_man:
# XXX: this is supposed to represent a scaled zero
return mpf_shift(fone, absolute_error), -1
if sum_man < 0:
sum_sign = 1
sum_man = -sum_man
else:
sum_sign = 0
sum_bc = bitcount(sum_man)
sum_accuracy = sum_exp + sum_bc - absolute_error
r = normalize(sum_sign, sum_man, sum_exp, sum_bc, target_prec,
round_nearest), sum_accuracy
#print "returning", to_str(r[0],50), r[1]
return r
def finalize_complex(re, im, prec):
assert re and im
if re == fzero and im == fzero:
raise ValueError("got complex zero with unknown accuracy")
size_re = fastlog(re)
size_im = fastlog(im)
# Convert fzeros to scaled zeros
if re == fzero:
re = mpf_shift(fone, size_im-prec)
size_re = fastlog(re)
elif im == fzero:
im = mpf_shift(fone, size_re-prec)
size_im = fastlog(im)
if size_re > size_im:
re_acc = prec
im_acc = prec + min(-(size_re - size_im), 0)
else:
im_acc = prec
re_acc = prec + min(-(size_im - size_re), 0)
return re, im, re_acc, im_acc
def finalize_complex(re, im, prec):
assert re and im
if re == fzero and im == fzero:
raise ValueError("got complex zero with unknown accuracy")
size_re = fastlog(re)
size_im = fastlog(im)
# Convert fzeros to scaled zeros
if re == fzero:
re = mpf_shift(fone, size_im - prec)
size_re = fastlog(re)
elif im == fzero:
im = mpf_shift(fone, size_re - prec)
size_im = fastlog(im)
if size_re > size_im:
re_acc = prec
im_acc = prec + min(-(size_re - size_im), 0)
else:
im_acc = prec
re_acc = prec + min(-(size_im - size_re), 0)
return re, im, re_acc, im_acc
def scaled_zero(mag, sign=1):
"""Return an mpf representing a power of two with magnitude ``mag``
and -1 for precision. Or, if ``mag`` is a scaled_zero tuple, then just
remove the sign from within the list that it was initially wrapped
in.
Examples
========
>>> from sympy.core.evalf import scaled_zero
>>> from sympy import Float
>>> z, p = scaled_zero(100)
>>> z, p
(([0], 1, 100, 1), -1)
>>> ok = scaled_zero(z)
>>> ok
(0, 1, 100, 1)
>>> Float(ok)
1.26765060022823e+30
>>> Float(ok, p)
0.e+30
>>> ok, p = scaled_zero(100, -1)
>>> Float(scaled_zero(ok), p)
-0.e+30
"""
if type(mag) is tuple and len(mag) == 4 and iszero(mag, scaled=True):
return (mag[0][0],) + mag[1:]
elif isinstance(mag, SYMPY_INTS):
if sign not in [-1, 1]:
raise ValueError("sign must be +/-1")
rv, p = mpf_shift(fone, mag), -1
s = 0 if sign == 1 else 1
rv = ([s],) + rv[1:]
return rv, p
else:
raise ValueError("scaled zero expects int or scaled_zero tuple.")
def scaled_zero(mag, sign=1):
"""Return an mpf representing a power of two with magnitude ``mag``
and -1 for precision. Or, if ``mag`` is a scaled_zero tuple, then just
remove the sign from within the list that it was initially wrapped
in.
Examples
========
>>> from sympy.core.evalf import scaled_zero
>>> from sympy import Float
>>> z, p = scaled_zero(100)
>>> z, p
(([0], 1, 100, 1), -1)
>>> ok = scaled_zero(z)
>>> ok
(0, 1, 100, 1)
>>> Float(ok)
1.26765060022823e+30
>>> Float(ok, p)
0.e+30
>>> ok, p = scaled_zero(100, -1)
>>> Float(scaled_zero(ok), p)
-0.e+30
"""
if type(mag) is tuple and len(mag) == 4 and iszero(mag, scaled=True):
return (mag[0][0],) + mag[1:]
elif isinstance(mag, SYMPY_INTS):
if sign not in [-1, 1]:
raise ValueError('sign must be +/-1')
rv, p = mpf_shift(fone, mag), -1
s = 0 if sign == 1 else 1
rv = ([s],) + rv[1:]
return rv, p
else:
raise ValueError('scaled zero expects int or scaled_zero tuple.')
def do_integral(expr, prec, options):
func = expr.args[0]
x, xlow, xhigh = expr.args[1]
orig = mp.prec
oldmaxprec = options.get('maxprec', DEFAULT_MAXPREC)
options['maxprec'] = min(oldmaxprec, 2*prec)
try:
mp.prec = prec+5
xlow = as_mpmath(xlow, prec+15, options)
xhigh = as_mpmath(xhigh, prec+15, options)
# Integration is like summation, and we can phone home from
# the integrand function to update accuracy summation style
# Note that this accuracy is inaccurate, since it fails
# to account for the variable quadrature weights,
# but it is better than nothing
have_part = [False, False]
max_real_term = [MINUS_INF]
max_imag_term = [MINUS_INF]
def f(t):
re, im, re_acc, im_acc = evalf(func, mp.prec, {'subs':{x:t}})
have_part[0] = re or have_part[0]
have_part[1] = im or have_part[1]
max_real_term[0] = max(max_real_term[0], fastlog(re))
max_imag_term[0] = max(max_imag_term[0], fastlog(im))
if im:
return mpc(re or fzero, im)
return mpf(re or fzero)
if options.get('quad') == 'osc':
A = C.Wild('A', exclude=[x])
B = C.Wild('B', exclude=[x])
D = C.Wild('D')
m = func.match(C.cos(A*x+B)*D)
if not m:
m = func.match(C.sin(A*x+B)*D)
if not m:
raise ValueError("An integrand of the form sin(A*x+B)*f(x) "
"or cos(A*x+B)*f(x) is required for oscillatory quadrature")
period = as_mpmath(2*S.Pi/m[A], prec+15, options)
result = quadosc(f, [xlow, xhigh], period=period)
# XXX: quadosc does not do error detection yet
quadrature_error = MINUS_INF
else:
result, quadrature_error = quadts(f, [xlow, xhigh], error=1)
quadrature_error = fastlog(quadrature_error._mpf_)
finally:
options['maxprec'] = oldmaxprec
mp.prec = orig
if have_part[0]:
re = result.real._mpf_
if re == fzero:
re = mpf_shift(fone, min(-prec,-max_real_term[0],-quadrature_error))
re_acc = -1
else:
re_acc = -max(max_real_term[0]-fastlog(re)-prec, quadrature_error)
else:
re, re_acc = None, None
if have_part[1]:
im = result.imag._mpf_
if im == fzero:
im = mpf_shift(fone, min(-prec,-max_imag_term[0],-quadrature_error))
im_acc = -1
else:
im_acc = -max(max_imag_term[0]-fastlog(im)-prec, quadrature_error)
else:
im, im_acc = None, None
result = re, im, re_acc, im_acc
return result
def do_integral(expr, prec, options):
func = expr.args[0]
x, xlow, xhigh = expr.args[1]
orig = mp.prec
oldmaxprec = options.get('maxprec', DEFAULT_MAXPREC)
options['maxprec'] = min(oldmaxprec, 2 * prec)
try:
mp.prec = prec + 5
xlow = as_mpmath(xlow, prec + 15, options)
xhigh = as_mpmath(xhigh, prec + 15, options)
# Integration is like summation, and we can phone home from
# the integrand function to update accuracy summation style
# Note that this accuracy is inaccurate, since it fails
# to account for the variable quadrature weights,
# but it is better than nothing
have_part = [False, False]
max_real_term = [MINUS_INF]
max_imag_term = [MINUS_INF]
def f(t):
re, im, re_acc, im_acc = evalf(func, mp.prec, {'subs': {x: t}})
have_part[0] = re or have_part[0]
have_part[1] = im or have_part[1]
max_real_term[0] = max(max_real_term[0], fastlog(re))
max_imag_term[0] = max(max_imag_term[0], fastlog(im))
if im:
return mpc(re or fzero, im)
return mpf(re or fzero)
if options.get('quad') == 'osc':
A = C.Wild('A', exclude=[x])
B = C.Wild('B', exclude=[x])
D = C.Wild('D')
m = func.match(C.cos(A * x + B) * D)
if not m:
m = func.match(C.sin(A * x + B) * D)
if not m:
raise ValueError(
"An integrand of the form sin(A*x+B)*f(x) "
"or cos(A*x+B)*f(x) is required for oscillatory quadrature"
)
period = as_mpmath(2 * S.Pi / m[A], prec + 15, options)
result = quadosc(f, [xlow, xhigh], period=period)
# XXX: quadosc does not do error detection yet
quadrature_error = MINUS_INF
else:
result, quadrature_error = quadts(f, [xlow, xhigh], error=1)
quadrature_error = fastlog(quadrature_error._mpf_)
finally:
options['maxprec'] = oldmaxprec
mp.prec = orig
if have_part[0]:
re = result.real._mpf_
if re == fzero:
re = mpf_shift(fone,
min(-prec, -max_real_term[0], -quadrature_error))
re_acc = -1
else:
re_acc = -max(max_real_term[0] - fastlog(re) - prec,
quadrature_error)
else:
re, re_acc = None, None
if have_part[1]:
im = result.imag._mpf_
if im == fzero:
im = mpf_shift(fone,
min(-prec, -max_imag_term[0], -quadrature_error))
im_acc = -1
else:
im_acc = -max(max_imag_term[0] - fastlog(im) - prec,
quadrature_error)
else:
im, im_acc = None, None
result = re, im, re_acc, im_acc
return result
