def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs(n, i) == c
assert catalan(n).rewrite(Product).subs(n, i).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2 *
x).rewrite(binomial) == binomial(4 * x, 2 * x) / (2 * x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8 / (3 * pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3 * x).rewrite(gamma) == 4**(
3 * x) * gamma(3 * x + Rational(1, 2)) / (sqrt(pi) * gamma(3 * x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2, ), 1)
assert catalan(n).rewrite(factorial) == factorial(
2 * n) / (factorial(n + 1) * factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(0, x + Rational(1, 2)) -
polygamma(0, x + 2) + log(4)) * catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(S.Half).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert str((re(c), im(c))) == '(0.398, -0.0209)'
def test_sympy_parser():
x = Symbol('x')
inputs = {
'2*x': 2 * x,
'3.00': Float(3),
'22/7': Rational(22, 7),
'2+3j': 2 + 3*I,
'exp(x)': exp(x),
'x!': factorial(x),
'x!!': factorial2(x),
'(x + 1)! - 1': factorial(x + 1) - 1,
'3.[3]': Rational(10, 3),
'.0[3]': Rational(1, 30),
'3.2[3]': Rational(97, 30),
'1.3[12]': Rational(433, 330),
'1 + 3.[3]': Rational(13, 3),
'1 + .0[3]': Rational(31, 30),
'1 + 3.2[3]': Rational(127, 30),
'.[0011]': Rational(1, 909),
'0.1[00102] + 1': Rational(366697, 333330),
'1.[0191]': Rational(10190, 9999),
'10!': 3628800,
'-(2)': -Integer(2),
'[-1, -2, 3]': [Integer(-1), Integer(-2), Integer(3)],
'Symbol("x").free_symbols': x.free_symbols,
"S('S(3).n(n=3)')": 3.00,
'factorint(12, visual=True)': Mul(
Pow(2, 2, evaluate=False),
Pow(3, 1, evaluate=False),
evaluate=False),
'Limit(sin(x), x, 0, dir="-")': Limit(sin(x), x, 0, dir='-'),
}
for text, result in inputs.items():
assert parse_expr(text) == result
def test_catalan():
n = Symbol('n', integer=True)
m = Symbol('n', integer=True, positive=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs(n, i) == c
assert catalan(n).rewrite(Product).subs(n, i).doit() == c
assert catalan(x) == catalan(x)
assert catalan(2*x).rewrite(binomial) == binomial(4*x, 2*x)/(2*x + 1)
assert catalan(Rational(1, 2)).rewrite(gamma) == 8/(3*pi)
assert catalan(Rational(1, 2)).rewrite(factorial).rewrite(gamma) ==\
8 / (3 * pi)
assert catalan(3*x).rewrite(gamma) == 4**(
3*x)*gamma(3*x + Rational(1, 2))/(sqrt(pi)*gamma(3*x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2,), 1)
assert catalan(n).rewrite(factorial) == factorial(2*n) / (factorial(n + 1)
* factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(
0, x + Rational(1, 2)) - polygamma(0, x + 2) + log(4))*catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(S.Half).evalf()
assert str(c) == '0.848826363156775'
c = catalan(I).evalf(3)
assert str((re(c), im(c))) == '(0.398, -0.0209)'
def psi_n(n, x, m, omega):
"""
Returns the wavefunction psi_{n} for the One-dimensional harmonic oscillator.
``n``
the "nodal" quantum number. Corresponds to the number of nodes in the
wavefunction. n >= 0
``x``
x coordinate
``m``
mass of the particle
``omega``
angular frequency of the oscillator
Examples
========
>>> from sympy.physics.qho_1d import psi_n
>>> from sympy import var
>>> var("x m omega")
(x, m, omega)
>>> psi_n(0, x, m, omega)
(m*omega)**(1/4)*exp(-m*omega*x**2/(2*hbar))/(hbar**(1/4)*pi**(1/4))
"""
# sympify arguments
n, x, m, omega = map(S, [n, x, m, omega])
nu = m * omega / hbar
# normalization coefficient
C = (nu / pi)**(S(1) / 4) * sqrt(1 / (2**n * factorial(n)))
return C * exp(-nu * x**2 / 2) * hermite(n, sqrt(nu) * x)
def _eval_nseries(self, x, n, logx, cdir=0):
from sympy.functions import factorial, RisingFactorial
from sympy import Order, Add
arg = self.args[2]
x0 = arg.limit(x, 0)
ap = self.args[0]
bq = self.args[1]
if x0 != 0:
return super()._eval_nseries(x, n, logx)
terms = []
for i in range(n):
num = 1
den = 1
for a in ap:
num *= RisingFactorial(a, i)
for b in bq:
den *= RisingFactorial(b, i)
terms.append(((num / den) * (arg**i)) / factorial(i))
return (Add(*terms) + Order(x**n, x))
def rank(self):
"""
Returns the lexicographic rank of the permutation.
Examples:
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0,1,2,3])
>>> p.rank
0
>>> p = Permutation([3,2,1,0])
>>> p.rank
23
"""
rank = 0
rho = self.array_form[:]
n = self.size - 1
psize = int(factorial(n))
for j in xrange(self.size - 1):
rank += rho[j]*psize
for i in xrange(j + 1, self.size):
if rho[i] > rho[j]:
rho[i] -= 1
psize //= n
n -= 1
return rank
def unrank_nonlex(self, n, r):
"""
This is a linear time unranking algorithm that does not
respect lexicographic order [3].
[3] See below
Examples:
>>> from sympy.combinatorics.permutations import Permutation
>>> Permutation.unrank_nonlex(4, 5)
Permutation([2, 0, 3, 1])
>>> Permutation.unrank_nonlex(4, -1)
Permutation([0, 1, 2, 3])
>>> Permutation.unrank_nonlex(6, 2)
Permutation([1, 5, 3, 4, 0, 2])
"""
def unrank1(n, r, a):
if n > 0:
a[n - 1], a[r % n] = a[r % n], a[n - 1]
unrank1(n - 1, r//n, a)
id_perm = range(n)
n = int(n)
r = int(r % factorial(n))
unrank1(n, r, id_perm)
return Permutation(id_perm)
def psi_n(n, x, m, omega):
"""
Returns the wavefunction psi_{n} for the One-dimensional harmonic oscillator.
``n``
the "nodal" quantum number. Corresponds to the number of nodes in the
wavefunction. n >= 0
``x``
x coordinate
``m``
mass of the particle
``omega``
angular frequency of the oscillator
:Examples
========
>>> from sympy.physics.qho_1d import psi_n
>>> from sympy import var
>>> var("x m omega")
(x, m, omega)
>>> psi_n(0, x, m, omega)
(m*omega)**(1/4)*exp(-m*omega*x**2/(2*hbar))/(hbar**(1/4)*pi**(1/4))
"""
# sympify arguments
n, x, m, omega = map(S, [n, x, m, omega])
nu = m * omega / hbar
# normalization coefficient
C = (nu/pi)**(S(1)/4) * sqrt(1/(2**n*factorial(n)))
return C * exp(-nu* x**2 /2) * hermite(n, sqrt(nu)*x)
def test_harmonic_rewrite():
n = Symbol("n")
m = Symbol("m")
assert harmonic(n).rewrite(digamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(trigamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(polygamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(
n,
3).rewrite(polygamma) == polygamma(2, n + 1) / 2 - polygamma(2, 1) / 2
assert harmonic(n, m).rewrite(polygamma) == (-1)**m * (
polygamma(m - 1, 1) - polygamma(m - 1, n + 1)) / factorial(m - 1)
assert expand_func(
harmonic(n + 4)
) == harmonic(n) + 1 / (n + 4) + 1 / (n + 3) + 1 / (n + 2) + 1 / (n + 1)
assert expand_func(harmonic(
n -
4)) == harmonic(n) - 1 / (n - 1) - 1 / (n - 2) - 1 / (n - 3) - 1 / n
assert harmonic(n,
m).rewrite("tractable") == harmonic(n,
m).rewrite(polygamma)
_k = Dummy("k")
assert harmonic(n).rewrite(Sum).dummy_eq(Sum(1 / _k, (_k, 1, n)))
assert harmonic(n, m).rewrite(Sum).dummy_eq(Sum(_k**(-m), (_k, 1, n)))
def test_Function():
assert mcode(f(x, y, z)) == "f[x, y, z]"
assert mcode(sin(x)**cos(x)) == "Sin[x]^Cos[x]"
assert mcode(conjugate(x)) == "Conjugate[x]"
assert mcode(Max(x, y, z) * Min(y, z)) == "Max[x, y, z]*Min[y, z]"
assert mcode(fresnelc(x)) == "FresnelC[x]"
assert mcode(fresnels(x)) == "FresnelS[x]"
assert mcode(gamma(x)) == "Gamma[x]"
assert mcode(uppergamma(x, y)) == "Gamma[x, y]"
assert mcode(polygamma(x, y)) == "PolyGamma[x, y]"
assert mcode(loggamma(x)) == "LogGamma[x]"
assert mcode(erf(x)) == "Erf[x]"
assert mcode(erfc(x)) == "Erfc[x]"
assert mcode(erfi(x)) == "Erfi[x]"
assert mcode(erf2(x, y)) == "Erf[x, y]"
assert mcode(expint(x, y)) == "ExpIntegralE[x, y]"
assert mcode(erfcinv(x)) == "InverseErfc[x]"
assert mcode(erfinv(x)) == "InverseErf[x]"
assert mcode(erf2inv(x, y)) == "InverseErf[x, y]"
assert mcode(Ei(x)) == "ExpIntegralEi[x]"
assert mcode(Ci(x)) == "CosIntegral[x]"
assert mcode(li(x)) == "LogIntegral[x]"
assert mcode(Si(x)) == "SinIntegral[x]"
assert mcode(Shi(x)) == "SinhIntegral[x]"
assert mcode(Chi(x)) == "CoshIntegral[x]"
assert mcode(beta(x, y)) == "Beta[x, y]"
assert mcode(factorial(x)) == "Factorial[x]"
assert mcode(factorial2(x)) == "Factorial2[x]"
assert mcode(subfactorial(x)) == "Subfactorial[x]"
assert mcode(FallingFactorial(x, y)) == "FactorialPower[x, y]"
assert mcode(RisingFactorial(x, y)) == "Pochhammer[x, y]"
assert mcode(catalan(x)) == "CatalanNumber[x]"
assert mcode(harmonic(x)) == "HarmonicNumber[x]"
assert mcode(harmonic(x, y)) == "HarmonicNumber[x, y]"
def _eval_rewrite_as_Sum(self, ap, bq, z):
from sympy.functions import factorial, RisingFactorial, Piecewise
n = C.Dummy("n", integer=True)
rfap = Tuple(*[RisingFactorial(a, n) for a in ap])
rfbq = Tuple(*[RisingFactorial(b, n) for b in bq])
coeff = Mul(*rfap) / Mul(*rfbq)
return Piecewise((C.Sum(coeff * z**n / factorial(n), (n, 0, oo)),
self.convergence_statement), (self, True))
def _eval_rewrite_as_Sum(self, ap, bq, z):
from sympy.functions import factorial, RisingFactorial, Piecewise
n = C.Dummy("n", integer=True)
rfap = Tuple(*[RisingFactorial(a, n) for a in ap])
rfbq = Tuple(*[RisingFactorial(b, n) for b in bq])
coeff = Mul(*rfap) / Mul(*rfbq)
return Piecewise((C.Sum(coeff * z ** n / factorial(n), (n, 0, oo)), self.convergence_statement), (self, True))
def R_nl(n, l, nu, r):
"""
Returns the radial wavefunction R_{nl} for a 3d isotropic harmonic
oscillator.
Parameters
==========
``n`` :
The "nodal" quantum number. Corresponds to the number of nodes in
the wavefunction. ``n >= 0``
``l`` :
The quantum number for orbital angular momentum.
``nu`` :
mass-scaled frequency: nu = m*omega/(2*hbar) where `m` is the mass
and `omega` the frequency of the oscillator.
(in atomic units ``nu == omega/2``)
``r`` :
Radial coordinate.
Examples
========
>>> from sympy.physics.sho import R_nl
>>> from sympy.abc import r, nu, l
>>> R_nl(0, 0, 1, r)
2*2**(3/4)*exp(-r**2)/pi**(1/4)
>>> R_nl(1, 0, 1, r)
4*2**(1/4)*sqrt(3)*(3/2 - 2*r**2)*exp(-r**2)/(3*pi**(1/4))
l, nu and r may be symbolic:
>>> R_nl(0, 0, nu, r)
2*2**(3/4)*sqrt(nu**(3/2))*exp(-nu*r**2)/pi**(1/4)
>>> R_nl(0, l, 1, r)
r**l*sqrt(2**(l + 3/2)*2**(l + 2)/factorial2(2*l + 1))*exp(-r**2)/pi**(1/4)
The normalization of the radial wavefunction is:
>>> from sympy import Integral, oo
>>> Integral(R_nl(0, 0, 1, r)**2*r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 0, 1, r)**2*r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 1, 1, r)**2*r**2, (r, 0, oo)).n()
1.00000000000000
"""
n, l, nu, r = map(S, [n, l, nu, r])
# formula uses n >= 1 (instead of nodal n >= 0)
n = n + 1
C = sqrt(
((2*nu)**(l + Rational(3, 2))*2**(n + l + 1)*factorial(n - 1))/
(sqrt(pi)*(factorial2(2*n + 2*l - 1)))
)
return C*r**(l)*exp(-nu*r**2)*assoc_laguerre(n - 1, l + S.Half, 2*nu*r**2)
def _eval_rewrite_as_Sum(self, ap, bq, z, **kwargs):
from sympy.concrete.summations import Sum
n = Dummy("n", integer=True)
rfap = Tuple(*[RisingFactorial(a, n) for a in ap])
rfbq = Tuple(*[RisingFactorial(b, n) for b in bq])
coeff = Mul(*rfap) / Mul(*rfbq)
return Piecewise((Sum(coeff * z**n / factorial(n),
(n, 0, oo)), self.convergence_statement),
(self, True))
def R_nl(n, l, nu, r):
"""
Returns the radial wavefunction R_{nl} for a 3d isotropic harmonic
oscillator.
``n``
the "nodal" quantum number. Corresponds to the number of nodes in
the wavefunction. n >= 0
``l``
the quantum number for orbital angular momentum
``nu``
mass-scaled frequency: nu = m*omega/(2*hbar) where `m` is the mass
and `omega` the frequency of the oscillator.
(in atomic units nu == omega/2)
``r``
Radial coordinate
Examples
========
>>> from sympy.physics.sho import R_nl
>>> from sympy import var
>>> var("r nu l")
(r, nu, l)
>>> R_nl(0, 0, 1, r)
2*2**(3/4)*exp(-r**2)/pi**(1/4)
>>> R_nl(1, 0, 1, r)
4*2**(1/4)*sqrt(3)*(-2*r**2 + 3/2)*exp(-r**2)/(3*pi**(1/4))
l, nu and r may be symbolic:
>>> R_nl(0, 0, nu, r)
2*2**(3/4)*sqrt(nu**(3/2))*exp(-nu*r**2)/pi**(1/4)
>>> R_nl(0, l, 1, r)
r**l*sqrt(2**(l + 3/2)*2**(l + 2)/factorial2(2*l + 1))*exp(-r**2)/pi**(1/4)
The normalization of the radial wavefunction is:
>>> from sympy import Integral, oo
>>> Integral(R_nl(0, 0, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 0, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 1, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
"""
n, l, nu, r = map(S, [n, l, nu, r])
# formula uses n >= 1 (instead of nodal n >= 0)
n = n + 1
C = sqrt(
((2 * nu) ** (l + Rational(3, 2)) * 2 ** (n + l + 1) * factorial(n - 1))
/ (sqrt(pi) * (factorial2(2 * n + 2 * l - 1)))
)
return C * r ** (l) * exp(-nu * r ** 2) * assoc_laguerre(n - 1, l + S(1) / 2, 2 * nu * r ** 2)
def monomial_count(V, N):
"""Computes the number of monomials of degree `N` in `#V` variables.
The number of monomials is given as `(#V + N)! / (#V! N!)`, e.g.::
>>> from sympy import monomials, monomial_count
>>> from sympy.abc import x, y
>>> monomial_count(2, 2)
6
>>> M = monomials([x, y], 2)
>>> sorted(M)
[1, x, y, x**2, y**2, x*y]
>>> len(M)
6
"""
return factorial(V + N) / factorial(V) / factorial(N)
def R_nl(n, l, nu, r):
"""
Returns the radial wavefunction R_{nl} for a 3d isotropic harmonic oscillator.
``n``
the "nodal" quantum number. Corresponds to the number of nodes in the
wavefunction. n >= 0
``l``
the quantum number for orbital angular momentum
``nu``
mass-scaled frequency: nu = m*omega/(2*hbar) where `m' is the mass and
`omega' the frequency of the oscillator. (in atomic units nu == omega/2)
``r``
Radial coordinate
:Examples:
>>> from sympy.physics.sho import R_nl
>>> from sympy import var
>>> var("r nu l")
(r, nu, l)
>>> R_nl(0, 0, 1, r)
2*2**(3/4)*exp(-r**2)/pi**(1/4)
>>> R_nl(1, 0, 1, r)
4*2**(1/4)*3**(1/2)*(3/2 - 2*r**2)*exp(-r**2)/(3*pi**(1/4))
l, nu and r may be symbolic:
>>> R_nl(0, 0, nu, r)
2*2**(3/4)*(nu**(3/2))**(1/2)*exp(-nu*r**2)/pi**(1/4)
>>> R_nl(0, l, 1, r)
r**l*(2**(2 + l)*2**(3/2 + l)/(1 + 2*l)!!)**(1/2)*exp(-r**2)/pi**(1/4)
The normalization of the radial wavefunction is::
>>> from sympy import Integral, oo
>>> Integral(R_nl(0, 0, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 0, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
>>> Integral(R_nl(1, 1, 1, r)**2 * r**2, (r, 0, oo)).n()
1.00000000000000
"""
n, l, nu, r = map(S, [n, l, nu, r])
# formula uses n >= 1 (instead of nodal n >= 0)
n = n + 1
C = sqrt(
((2 * nu)**(l + Rational(3, 2)) * 2**(n + l + 1) * factorial(n - 1)) /
(sqrt(pi) * (factorial2(2 * n + 2 * l - 1))))
return C * r**(l) * exp(-nu * r**2) * laguerre_l(n - 1, l + S(1) / 2,
2 * nu * r**2)
def monomial_count(V, N):
"""Computes the number of monomials of degree `N` in `#V` variables.
The number of monomials is given as `(#V + N)! / (#V! N!)`, e.g.::
>>> from sympy import monomials, monomial_count
>>> from sympy.abc import x, y
>>> monomial_count(2, 2)
6
>>> M = monomials([x, y], 2)
>>> sorted(M)
[1, x, y, x**2, y**2, x*y]
>>> len(M)
6
"""
return factorial(V + N) / factorial(V) / factorial(N)
def monomial_count(V, N):
"""Computes the number of monomials of degree N in #V variables.
The number of monomials is given as (#V + N)! / (#V! N!), e.g.:
>>> from sympy.polys.monomial import monomial_count, monomials
>>> from sympy.abc import x, y
>>> monomial_count(2, 2)
6
>>> M = monomials([x, y], 2)
>>> print M
set([1, x, y, x*y, x**2, y**2])
>>> len(M)
6
"""
return factorial(V + N) / factorial(V) / factorial(N)
def monomial_count(V, N):
"""Computes the number of monomials of degree N in #V variables.
The number of monomials is given as (#V + N)! / (#V! N!), eg:
>>> from sympy import *
>>> x,y = symbols('xy')
>>> monomial_count(2, 2)
6
>>> M = monomials([x, y], 2)
>>> print M
[1, x, y, x**2, y**2, x*y]
>>> len(M)
6
"""
return factorial(V + N) / factorial(V) / factorial(N)
def monomial_count(V, N):
"""Computes the number of monomials of degree N in #V variables.
The number of monomials is given as (#V + N)! / (#V! N!), eg:
>>> from sympy import *
>>> x,y = symbols('xy')
>>> monomial_count(2, 2)
6
>>> M = monomials([x, y], 2)
>>> print M
[1, x, y, x**2, y**2, x*y]
>>> len(M)
6
"""
return factorial(V + N) / factorial(V) / factorial(N)
def unrank_lex(self, size, rank):
"""
Lexicographic permutation unranking.
Examples:
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation.unrank_lex(5,10)
>>> a.rank
10
>>> a
Permutation([0, 2, 4, 1, 3])
"""
perm_array = [0] * size
for i in xrange(size):
d = (rank % int(factorial(i + 1))) / int(factorial(i))
rank = rank - d*int(factorial(i))
perm_array[size - i - 1] = d
for j in xrange(size - i, size):
if perm_array[j] > d-1:
perm_array[j] += 1
return Permutation(perm_array)
def coherent_state(n, alpha):
"""
Returns <n|alpha> for the coherent states of 1D harmonic oscillator.
See http://en.wikipedia.org/wiki/Coherent_states
``n``
the "nodal" quantum number
``alpha``
the eigen value of annihilation operator
"""
return exp(- Abs(alpha)**2/2)*(alpha**n)/sqrt(factorial(n))
def unrank_lex(self, size, rank):
"""
Lexicographic permutation unranking.
Examples:
>>> from sympy.combinatorics.permutations import Permutation
>>> a = Permutation.unrank_lex(5,10)
>>> a.rank
10
>>> a
Permutation([0, 2, 4, 1, 3])
"""
perm_array = [0] * size
perm_array[size - 1] = 1
for i in xrange(size - 1):
d = (rank % int(factorial(i + 1))) / int(factorial(i))
rank = rank - d * int(factorial(i))
perm_array[size - i - 1] = d + 1
for j in xrange(size - i, size):
if perm_array[j] > d:
perm_array[j] += 1
return Permutation(perm_array)
def test_catalan():
n = Symbol("n", integer=True)
m = Symbol("m", integer=True, positive=True)
k = Symbol("k", integer=True, nonnegative=True)
p = Symbol("p", nonnegative=True)
catalans = [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786]
for i, c in enumerate(catalans):
assert catalan(i) == c
assert catalan(n).rewrite(factorial).subs(n, i) == c
assert catalan(n).rewrite(Product).subs(n, i).doit() == c
assert unchanged(catalan, x)
assert catalan(2 *
x).rewrite(binomial) == binomial(4 * x, 2 * x) / (2 * x + 1)
assert catalan(S.Half).rewrite(gamma) == 8 / (3 * pi)
assert catalan(S.Half).rewrite(factorial).rewrite(gamma) == 8 / (3 * pi)
assert catalan(3 * x).rewrite(gamma) == 4**(
3 * x) * gamma(3 * x + S.Half) / (sqrt(pi) * gamma(3 * x + 2))
assert catalan(x).rewrite(hyper) == hyper((-x + 1, -x), (2, ), 1)
assert catalan(n).rewrite(factorial) == factorial(
2 * n) / (factorial(n + 1) * factorial(n))
assert isinstance(catalan(n).rewrite(Product), catalan)
assert isinstance(catalan(m).rewrite(Product), Product)
assert diff(catalan(x), x) == (polygamma(0, x + S.Half) -
polygamma(0, x + 2) + log(4)) * catalan(x)
assert catalan(x).evalf() == catalan(x)
c = catalan(S.Half).evalf()
assert str(c) == "0.848826363156775"
c = catalan(I).evalf(3)
assert str((re(c), im(c))) == "(0.398, -0.0209)"
# Assumptions
assert catalan(p).is_positive is True
assert catalan(k).is_integer is True
assert catalan(m + 3).is_composite is True
def test_Function():
assert mcode(sin(x) ** cos(x)) == "sin(x).^cos(x)"
assert mcode(sign(x)) == "sign(x)"
assert mcode(exp(x)) == "exp(x)"
assert mcode(log(x)) == "log(x)"
assert mcode(factorial(x)) == "factorial(x)"
assert mcode(floor(x)) == "floor(x)"
assert mcode(atan2(y, x)) == "atan2(y, x)"
assert mcode(beta(x, y)) == 'beta(x, y)'
assert mcode(polylog(x, y)) == 'polylog(x, y)'
assert mcode(harmonic(x)) == 'harmonic(x)'
assert mcode(bernoulli(x)) == "bernoulli(x)"
assert mcode(bernoulli(x, y)) == "bernoulli(x, y)"
def test_Function():
assert mcode(sin(x)**cos(x)) == "sin(x).^cos(x)"
assert mcode(sign(x)) == "sign(x)"
assert mcode(exp(x)) == "exp(x)"
assert mcode(log(x)) == "log(x)"
assert mcode(factorial(x)) == "factorial(x)"
assert mcode(floor(x)) == "floor(x)"
assert mcode(atan2(y, x)) == "atan2(y, x)"
assert mcode(beta(x, y)) == 'beta(x, y)'
assert mcode(polylog(x, y)) == 'polylog(x, y)'
assert mcode(harmonic(x)) == 'harmonic(x)'
assert mcode(bernoulli(x)) == "bernoulli(x)"
assert mcode(bernoulli(x, y)) == "bernoulli(x, y)"
def euler_maclaurin(self, n=0):
"""
Return n-th order Euler-Maclaurin approximation of self.
The 0-th order approximation is simply the corresponding
integral
"""
f, i, a, b = self.f, self.i, self.a, self.b
x = Symbol('x', dummy=True)
s = Basic.Integral(f.subs(i, x), (x, a, b)).doit()
if n > 0:
s += (f.subs(i, a) + f.subs(i, b))/2
for k in range(1, n):
g = f.diff(i, 2*k-1)
B = Basic.bernoulli
s += B(2*k)/factorial(2*k)*(g.subs(i,b)-g.subs(i,a))
return s
def test_sympy_parser():
x = Symbol('x')
inputs = {
'2*x': 2 * x,
'3.00': Float(3),
'22/7': Rational(22, 7),
'2+3j': 2 + 3*I,
'exp(x)': exp(x),
'x!': factorial(x),
'3.[3]': Rational(10, 3),
'10!': 3628800,
'(_kern)': Symbol('_kern'),
'-(2)': -Integer(2),
'[-1, -2, 3]': [Integer(-1), Integer(-2), Integer(3)]
}
for text, result in inputs.items():
assert parse_expr(text) == result
def test_sympy_parser():
x = Symbol("x")
inputs = {
"2*x": 2 * x,
"3.00": Float(3),
"22/7": Rational(22, 7),
"2+3j": 2 + 3 * I,
"exp(x)": exp(x),
"x!": factorial(x),
"3.[3]": Rational(10, 3),
"10!": 3628800,
"-(2)": -Integer(2),
"[-1, -2, 3]": [Integer(-1), Integer(-2), Integer(3)],
'Symbol("x").free_symbols': x.free_symbols,
"S('S(3).n(n=3)')": 3.00,
"factorint(12, visual=True)": Mul(Pow(2, 2, evaluate=False), Pow(3, 1, evaluate=False), evaluate=False),
'Limit(sin(x), x, 0, dir="-")': Limit(sin(x), x, 0, dir="-"),
}
for text, result in inputs.items():
assert parse_expr(text) == result
def rank(self):
"""
Returns the lexicographic rank of the permutation.
Examples:
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([0,1,2,3])
>>> p.rank
0
>>> p = Permutation([3,2,1,0])
>>> p.rank
23
"""
rank = 0
rho = self.array_form[:]
for j in xrange(self.size - 1):
rank += (rho[j]) * int(factorial(self.size - j - 1))
for i in xrange(j + 1, self.size):
if rho[i] > rho[j]:
rho[i] = rho[i] - 1
return rank
def test_sympy_parser():
x = Symbol('x')
inputs = {
'2*x': 2 * x,
'3.00': Float(3),
'22/7': Rational(22, 7),
'2+3j': 2 + 3*I,
'exp(x)': exp(x),
'x!': factorial(x),
'3.[3]': Rational(10, 3),
'10!': 3628800,
'-(2)': -Integer(2),
'[-1, -2, 3]': [Integer(-1), Integer(-2), Integer(3)],
'Symbol("x").free_symbols': x.free_symbols,
"S('S(3).n(n=3)')": 3.00,
'factorint(12, visual=True)': Mul(
Pow(2, 2, evaluate=False),
Pow(3, 1, evaluate=False),
evaluate=False),
'Limit(sin(x), x, 0, dir="-")': Limit(sin(x), x, 0, dir='-'),
}
for text, result in inputs.items():
assert parse_expr(text) == result
def test_harmonic_rewrite_polygamma():
n = Symbol("n")
m = Symbol("m")
assert harmonic(n).rewrite(digamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(trigamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(polygamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(
n,
3).rewrite(polygamma) == polygamma(2, n + 1) / 2 - polygamma(2, 1) / 2
assert harmonic(n, m).rewrite(polygamma) == (-1)**m * (
polygamma(m - 1, 1) - polygamma(m - 1, n + 1)) / factorial(m - 1)
assert expand_func(
harmonic(n + 4)
) == harmonic(n) + 1 / (n + 4) + 1 / (n + 3) + 1 / (n + 2) + 1 / (n + 1)
assert expand_func(harmonic(
n -
4)) == harmonic(n) - 1 / (n - 1) - 1 / (n - 2) - 1 / (n - 3) - 1 / n
assert harmonic(n,
m).rewrite("tractable") == harmonic(n,
m).rewrite(polygamma)
def euler_maclaurin(self, m=0, n=0, eps=0, eval_integral=True):
"""
Return an Euler-Maclaurin approximation of self, where m is the
number of leading terms to sum directly and n is the number of
terms in the tail.
With m = n = 0, this is simply the corresponding integral
plus a first-order endpoint correction.
Returns (s, e) where s is the Euler-Maclaurin approximation
and e is the estimated error (taken to be the magnitude of
the first omitted term in the tail):
>>> from sympy.abc import k, a, b
>>> from sympy import Sum
>>> Sum(1/k, (k, 2, 5)).doit().evalf()
1.28333333333333
>>> s, e = Sum(1/k, (k, 2, 5)).euler_maclaurin()
>>> s
-log(2) + 7/20 + log(5)
>>> from sympy import sstr
>>> print(sstr((s.evalf(), e.evalf()), full_prec=True))
(1.26629073187415, 0.0175000000000000)
The endpoints may be symbolic:
>>> s, e = Sum(1/k, (k, a, b)).euler_maclaurin()
>>> s
-log(a) + log(b) + 1/(2*b) + 1/(2*a)
>>> e
Abs(1/(12*b**2) - 1/(12*a**2))
If the function is a polynomial of degree at most 2n+1, the
Euler-Maclaurin formula becomes exact (and e = 0 is returned):
>>> Sum(k, (k, 2, b)).euler_maclaurin()
(b**2/2 + b/2 - 1, 0)
>>> Sum(k, (k, 2, b)).doit()
b**2/2 + b/2 - 1
With a nonzero eps specified, the summation is ended
as soon as the remainder term is less than the epsilon.
"""
from sympy.functions import bernoulli, factorial
from sympy.integrals import Integral
m = int(m)
n = int(n)
f = self.function
if len(self.limits) != 1:
raise ValueError("More than 1 limit")
i, a, b = self.limits[0]
if (a > b) == True:
if a - b == 1:
return S.Zero, S.Zero
a, b = b + 1, a - 1
f = -f
s = S.Zero
if m:
if b.is_Integer and a.is_Integer:
m = min(m, b - a + 1)
if not eps or f.is_polynomial(i):
for k in range(m):
s += f.subs(i, a + k)
else:
term = f.subs(i, a)
if term:
test = abs(term.evalf(3)) < eps
if test == True:
return s, abs(term)
elif not (test == False):
# a symbolic Relational class, can't go further
return term, S.Zero
s += term
for k in range(1, m):
term = f.subs(i, a + k)
if abs(term.evalf(3)) < eps and term != 0:
return s, abs(term)
s += term
if b - a + 1 == m:
return s, S.Zero
a += m
x = Dummy('x')
I = Integral(f.subs(i, x), (x, a, b))
if eval_integral:
I = I.doit()
s += I
def fpoint(expr):
if b is S.Infinity:
return expr.subs(i, a), 0
return expr.subs(i, a), expr.subs(i, b)
fa, fb = fpoint(f)
iterm = (fa + fb)/2
g = f.diff(i)
for k in range(1, n + 2):
ga, gb = fpoint(g)
term = bernoulli(2*k)/factorial(2*k)*(gb - ga)
if (eps and term and abs(term.evalf(3)) < eps) or (k > n):
break
s += term
g = g.diff(i, 2, simplify=False)
return s + iterm, abs(term)
def test_sympy_parser():
x = Symbol("x")
inputs = {
"2*x":
2 * x,
"3.00":
Float(3),
"22/7":
Rational(22, 7),
"2+3j":
2 + 3 * I,
"exp(x)":
exp(x),
"x!":
factorial(x),
"x!!":
factorial2(x),
"(x + 1)! - 1":
factorial(x + 1) - 1,
"3.[3]":
Rational(10, 3),
".0[3]":
Rational(1, 30),
"3.2[3]":
Rational(97, 30),
"1.3[12]":
Rational(433, 330),
"1 + 3.[3]":
Rational(13, 3),
"1 + .0[3]":
Rational(31, 30),
"1 + 3.2[3]":
Rational(127, 30),
".[0011]":
Rational(1, 909),
"0.1[00102] + 1":
Rational(366697, 333330),
"1.[0191]":
Rational(10190, 9999),
"10!":
3628800,
"-(2)":
-Integer(2),
"[-1, -2, 3]": [Integer(-1), Integer(-2),
Integer(3)],
'Symbol("x").free_symbols':
x.free_symbols,
"S('S(3).n(n=3)')":
3.00,
"factorint(12, visual=True)":
Mul(Pow(2, 2, evaluate=False),
Pow(3, 1, evaluate=False),
evaluate=False),
'Limit(sin(x), x, 0, dir="-")':
Limit(sin(x), x, 0, dir="-"),
}
for text, result in inputs.items():
assert parse_expr(text) == result
raises(TypeError, lambda: parse_expr("x", standard_transformations))
raises(TypeError, lambda: parse_expr("x", transformations=lambda x, y: 1))
raises(TypeError,
lambda: parse_expr("x", transformations=(lambda x, y: 1,
)))
raises(TypeError, lambda: parse_expr("x", transformations=((), )))
raises(TypeError, lambda: parse_expr("x", {}, [], []))
raises(TypeError, lambda: parse_expr("x", [], [], {}))
raises(TypeError, lambda: parse_expr("x", [], [], {}))
def euler_maclaurin(self, m=0, n=0, eps=0, eval_integral=True):
"""
Return an Euler-Maclaurin approximation of self, where m is the
number of leading terms to sum directly and n is the number of
terms in the tail.
With m = n = 0, this is simply the corresponding integral
plus a first-order endpoint correction.
Returns (s, e) where s is the Euler-Maclaurin approximation
and e is the estimated error (taken to be the magnitude of
the first omitted term in the tail):
>>> from sympy.abc import k, a, b
>>> from sympy import Sum
>>> Sum(1/k, (k, 2, 5)).doit().evalf()
1.28333333333333
>>> s, e = Sum(1/k, (k, 2, 5)).euler_maclaurin()
>>> s
-log(2) + 7/20 + log(5)
>>> from sympy import sstr
>>> print(sstr((s.evalf(), e.evalf()), full_prec=True))
(1.26629073187415, 0.0175000000000000)
The endpoints may be symbolic:
>>> s, e = Sum(1/k, (k, a, b)).euler_maclaurin()
>>> s
-log(a) + log(b) + 1/(2*b) + 1/(2*a)
>>> e
Abs(1/(12*b**2) - 1/(12*a**2))
If the function is a polynomial of degree at most 2n+1, the
Euler-Maclaurin formula becomes exact (and e = 0 is returned):
>>> Sum(k, (k, 2, b)).euler_maclaurin()
(b**2/2 + b/2 - 1, 0)
>>> Sum(k, (k, 2, b)).doit()
b**2/2 + b/2 - 1
With a nonzero eps specified, the summation is ended
as soon as the remainder term is less than the epsilon.
"""
from sympy.functions import bernoulli, factorial
from sympy.integrals import Integral
m = int(m)
n = int(n)
f = self.function
if len(self.limits) != 1:
raise ValueError("More than 1 limit")
i, a, b = self.limits[0]
if (a > b) == True:
if a - b == 1:
return S.Zero, S.Zero
a, b = b + 1, a - 1
f = -f
s = S.Zero
if m:
if b.is_Integer and a.is_Integer:
m = min(m, b - a + 1)
if not eps or f.is_polynomial(i):
for k in range(m):
s += f.subs(i, a + k)
else:
term = f.subs(i, a)
if term:
test = abs(term.evalf(3)) < eps
if test == True:
return s, abs(term)
elif not (test == False):
# a symbolic Relational class, can't go further
return term, S.Zero
s += term
for k in range(1, m):
term = f.subs(i, a + k)
if abs(term.evalf(3)) < eps and term != 0:
return s, abs(term)
s += term
if b - a + 1 == m:
return s, S.Zero
a += m
x = Dummy('x')
I = Integral(f.subs(i, x), (x, a, b))
if eval_integral:
I = I.doit()
s += I
def fpoint(expr):
if b is S.Infinity:
return expr.subs(i, a), 0
return expr.subs(i, a), expr.subs(i, b)
fa, fb = fpoint(f)
iterm = (fa + fb)/2
g = f.diff(i)
for k in range(1, n + 2):
ga, gb = fpoint(g)
term = bernoulli(2*k)/factorial(2*k)*(gb - ga)
if (eps and term and abs(term.evalf(3)) < eps) or (k > n):
break
s += term
g = g.diff(i, 2, simplify=False)
return s + iterm, abs(term)
def test_rcode_functions():
assert rcode(sin(x) ** cos(x)) == "sin(x)^cos(x)"
assert rcode(factorial(x) + gamma(y)) == "factorial(x) + gamma(y)"
assert rcode(beta(Min(x, y), Max(x, y))) == "beta(min(x, y), max(x, y))"
def test_harmonic_rewrite_polygamma():
n = Symbol("n")
m = Symbol("m")
assert harmonic(n).rewrite(digamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(trigamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n).rewrite(polygamma) == polygamma(0, n + 1) + EulerGamma
assert harmonic(n,3).rewrite(polygamma) == polygamma(2, n + 1)/2 - polygamma(2, 1)/2
assert harmonic(n,m).rewrite(polygamma) == (-1)**m*(polygamma(m - 1, 1) - polygamma(m - 1, n + 1))/factorial(m - 1)
assert expand_func(harmonic(n+4)) == harmonic(n) + 1/(n + 4) + 1/(n + 3) + 1/(n + 2) + 1/(n + 1)
assert expand_func(harmonic(n-4)) == harmonic(n) - 1/(n - 1) - 1/(n - 2) - 1/(n - 3) - 1/n
assert harmonic(n, m).rewrite("tractable") == harmonic(n, m).rewrite(polygamma)
def test_rcode_functions():
assert rcode(sin(x)**cos(x)) == "sin(x)^cos(x)"
assert rcode(factorial(x) + gamma(y)) == "factorial(x) + gamma(y)"
assert rcode(beta(Min(x, y), Max(x, y))) == "beta(min(x, y), max(x, y))"