Python functions.gamma函数代码示例

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 gamma_rat(x):
     # helper to simplify ratios of gammas
     was = x.count(gamma)
     xx = x.replace(gamma, lambda n: _rf(1, (n - 1).expand()
         ).replace(_rf, lambda a, b: gamma(a + b)/gamma(a)))
     if xx.count(gamma) < was:
         x = xx
     return x

def test_ccode_exceptions():
    assert ccode(gamma(x), standard='C99') == "tgamma(x)"
    gamma_c89 = ccode(gamma(x), standard='C89')
    assert 'not supported in c' in gamma_c89.lower()
    gamma_c89 = ccode(gamma(x), standard='C89', allow_unknown_functions=False)
    assert 'not supported in c' in gamma_c89.lower()
    gamma_c89 = ccode(gamma(x), standard='C89', allow_unknown_functions=True)
    assert not 'not supported in c' in gamma_c89.lower()
    assert ccode(ceiling(x)) == "ceil(x)"
    assert ccode(Abs(x)) == "fabs(x)"
    assert ccode(gamma(x)) == "tgamma(x)"
    r, s = symbols('r,s', real=True)
    assert ccode(Mod(ceiling(r), ceiling(s))) == "((ceil(r)) % (ceil(s)))"
    assert ccode(Mod(r, s)) == "fmod(r, s)"

def test_catalan():
    assert catalan(1) == 1
    assert catalan(2) == 2
    assert catalan(3) == 5
    assert catalan(4) == 14

    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(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 diff(catalan(x), x) == (polygamma(
        0, x + Rational(1, 2)) - polygamma(0, x + 2) + log(4))*catalan(x)

    c = catalan(0.5).evalf()
    assert str(c) == '0.848826363156775'

def test_C99CodePrinter__precision():
    n = symbols('n', integer=True)
    f32_printer = C99CodePrinter(dict(type_aliases={real: float32}))
    f64_printer = C99CodePrinter(dict(type_aliases={real: float64}))
    f80_printer = C99CodePrinter(dict(type_aliases={real: float80}))
    assert f32_printer.doprint(sin(x+2.1)) == 'sinf(x + 2.1F)'
    assert f64_printer.doprint(sin(x+2.1)) == 'sin(x + 2.1000000000000001)'
    assert f80_printer.doprint(sin(x+Float('2.0'))) == 'sinl(x + 2.0L)'

    for printer, suffix in zip([f32_printer, f64_printer, f80_printer], ['f', '', 'l']):
        def check(expr, ref):
            assert printer.doprint(expr) == ref.format(s=suffix, S=suffix.upper())
        check(Abs(n), 'abs(n)')
        check(Abs(x + 2.0), 'fabs{s}(x + 2.0{S})')
        check(sin(x + 4.0)**cos(x - 2.0), 'pow{s}(sin{s}(x + 4.0{S}), cos{s}(x - 2.0{S}))')
        check(exp(x*8.0), 'exp{s}(8.0{S}*x)')
        check(exp2(x), 'exp2{s}(x)')
        check(expm1(x*4.0), 'expm1{s}(4.0{S}*x)')
        check(Mod(n, 2), '((n) % (2))')
        check(Mod(2*n + 3, 3*n + 5), '((2*n + 3) % (3*n + 5))')
        check(Mod(x + 2.0, 3.0), 'fmod{s}(1.0{S}*x + 2.0{S}, 3.0{S})')
        check(Mod(x, 2.0*x + 3.0), 'fmod{s}(1.0{S}*x, 2.0{S}*x + 3.0{S})')
        check(log(x/2), 'log{s}((1.0{S}/2.0{S})*x)')
        check(log10(3*x/2), 'log10{s}((3.0{S}/2.0{S})*x)')
        check(log2(x*8.0), 'log2{s}(8.0{S}*x)')
        check(log1p(x), 'log1p{s}(x)')
        check(2**x, 'pow{s}(2, x)')
        check(2.0**x, 'pow{s}(2.0{S}, x)')
        check(x**3, 'pow{s}(x, 3)')
        check(x**4.0, 'pow{s}(x, 4.0{S})')
        check(sqrt(3+x), 'sqrt{s}(x + 3)')
        check(Cbrt(x-2.0), 'cbrt{s}(x - 2.0{S})')
        check(hypot(x, y), 'hypot{s}(x, y)')
        check(sin(3.*x + 2.), 'sin{s}(3.0{S}*x + 2.0{S})')
        check(cos(3.*x - 1.), 'cos{s}(3.0{S}*x - 1.0{S})')
        check(tan(4.*y + 2.), 'tan{s}(4.0{S}*y + 2.0{S})')
        check(asin(3.*x + 2.), 'asin{s}(3.0{S}*x + 2.0{S})')
        check(acos(3.*x + 2.), 'acos{s}(3.0{S}*x + 2.0{S})')
        check(atan(3.*x + 2.), 'atan{s}(3.0{S}*x + 2.0{S})')
        check(atan2(3.*x, 2.*y), 'atan2{s}(3.0{S}*x, 2.0{S}*y)')

        check(sinh(3.*x + 2.), 'sinh{s}(3.0{S}*x + 2.0{S})')
        check(cosh(3.*x - 1.), 'cosh{s}(3.0{S}*x - 1.0{S})')
        check(tanh(4.0*y + 2.), 'tanh{s}(4.0{S}*y + 2.0{S})')
        check(asinh(3.*x + 2.), 'asinh{s}(3.0{S}*x + 2.0{S})')
        check(acosh(3.*x + 2.), 'acosh{s}(3.0{S}*x + 2.0{S})')
        check(atanh(3.*x + 2.), 'atanh{s}(3.0{S}*x + 2.0{S})')
        check(erf(42.*x), 'erf{s}(42.0{S}*x)')
        check(erfc(42.*x), 'erfc{s}(42.0{S}*x)')
        check(gamma(x), 'tgamma{s}(x)')
        check(loggamma(x), 'lgamma{s}(x)')

        check(ceiling(x + 2.), "ceil{s}(x + 2.0{S})")
        check(floor(x + 2.), "floor{s}(x + 2.0{S})")
        check(fma(x, y, -z), 'fma{s}(x, y, -z)')
        check(Max(x, 8.0, x**4.0), 'fmax{s}(8.0{S}, fmax{s}(x, pow{s}(x, 4.0{S})))')
        check(Min(x, 2.0), 'fmin{s}(2.0{S}, x)')

def test_rcode_exceptions():
    assert rcode(ceiling(x)) == "ceiling(x)"
    assert rcode(Abs(x)) == "abs(x)"
    assert rcode(gamma(x)) == "gamma(x)"

def test_ccode_exceptions():
    assert ccode(ceiling(x)) == "ceil(x)"
    assert ccode(Abs(x)) == "fabs(x)"
    assert ccode(gamma(x)) == "tgamma(x)"

def test_functions_special():
    assert oclcode(erf(x)) == "erf(x)"
    assert oclcode(erfc(x)) == "erfc(x)"
    assert oclcode(gamma(x)) == "tgamma(x)"
    assert oclcode(loggamma(x)) == "lgamma(x)"

def test_ccode_exceptions():
    assert ccode(gamma(x), standard='C99') == "tgamma(x)"
    assert 'not supported in c' in ccode(gamma(x), standard='C89').lower()
    assert ccode(ceiling(x)) == "ceil(x)"
    assert ccode(Abs(x)) == "fabs(x)"
    assert ccode(gamma(x)) == "tgamma(x)"

def _gammasimp(expr, as_comb):
    """
    Helper function for gammasimp and combsimp.

    Simplifies expressions written in terms of gamma function. If
    as_comb is True, it tries to preserve integer arguments. See
    docstring of gammasimp for more information. This was part of
    combsimp() in combsimp.py.
    """

    expr = expr.replace(gamma,
        lambda n: _rf(1, (n - 1).expand()))

    if as_comb:
        expr = expr.replace(_rf,
            lambda a, b: gamma(b + 1))
    else:
        expr = expr.replace(_rf,
            lambda a, b: gamma(a + b)/gamma(a))

    def rule(n, k):
        coeff, rewrite = S.One, False

        cn, _n = n.as_coeff_Add()

        if _n and cn.is_Integer and cn:
            coeff *= _rf(_n + 1, cn)/_rf(_n - k + 1, cn)
            rewrite = True
            n = _n

        # this sort of binomial has already been removed by
        # rising factorials but is left here in case the order
        # of rule application is changed
        if k.is_Add:
            ck, _k = k.as_coeff_Add()
            if _k and ck.is_Integer and ck:
                coeff *= _rf(n - ck - _k + 1, ck)/_rf(_k + 1, ck)
                rewrite = True
                k = _k

        if count_ops(k) > count_ops(n - k):
            rewrite = True
            k = n - k

        if rewrite:
            return coeff*binomial(n, k)

    expr = expr.replace(binomial, rule)

    def rule_gamma(expr, level=0):
        """ Simplify products of gamma functions further. """

        if expr.is_Atom:
            return expr

        def gamma_rat(x):
            # helper to simplify ratios of gammas
            was = x.count(gamma)
            xx = x.replace(gamma, lambda n: _rf(1, (n - 1).expand()
                ).replace(_rf, lambda a, b: gamma(a + b)/gamma(a)))
            if xx.count(gamma) < was:
                x = xx
            return x

        def gamma_factor(x):
            # return True if there is a gamma factor in shallow args
            if isinstance(x, gamma):
                return True
            if x.is_Add or x.is_Mul:
                return any(gamma_factor(xi) for xi in x.args)
            if x.is_Pow and (x.exp.is_integer or x.base.is_positive):
                return gamma_factor(x.base)
            return False

        # recursion step
        if level == 0:
            expr = expr.func(*[rule_gamma(x, level + 1) for x in expr.args])
            level += 1

        if not expr.is_Mul:
            return expr

        # non-commutative step
        if level == 1:
            args, nc = expr.args_cnc()
            if not args:
                return expr
            if nc:
                return rule_gamma(Mul._from_args(args), level + 1)*Mul._from_args(nc)
            level += 1

        # pure gamma handling, not factor absorption
        if level == 2:
            T, F = sift(expr.args, gamma_factor, binary=True)
            gamma_ind = Mul(*F)
            d = Mul(*T)

            nd, dd = d.as_numer_denom()
            for ipass in range(2):
                args = list(ordered(Mul.make_args(nd)))
#.........这里部分代码省略.........

 def fdiff(self, argindex=1):
     if argindex == 1:
         from sympy.functions import gamma, polygamma
         return gamma(self[0]+1)*polygamma(0,self[0]+1)
     else:
         raise ArgumentIndexError(self, argindex)

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_ccode_functions():
    assert ccode(sin(x) ** cos(x)) == "pow(sin(x), cos(x))"
    assert ccode(ceiling(x)) == "ceil(x)"
    assert ccode(Abs(x)) == "fabs(x)"
    assert ccode(gamma(x)) == "tgamma(x)"