Do you know what the right answer should be? It gives 0 in Mateusz's new-polys branch.
Aaron Meurer On Tue, May 28, 2013 at 11:30 AM, Will Furnass <[email protected]> wrote: > Thanks Aaron. My code now looks as follows (T is now a lambda function and > the integral is evaluated over t=0..oo): > > ... > T = lambda t: Piecewise((0, t < 0), (k * D * pi * dx * expr8 / Q, t >= 0)) > > curve_expr = integrate(T(t - (x/V)), (x, 0, L)) > vals = { > P : 0.00022, > k : 0.5, > tau_s : 0.01, > tau_a : 2.0, > Q : 0.01, > D : 0.125, > L : 1225, > n : 2, > dx : 1} > Integral(curve_expr, (t, 0, oo)).subs(vals).doit() > > I now get the following error, regardless of whether I use the git master or > mattpap's new-polys branch: > > AttributeError Traceback (most recent call last) > <ipython-input-7-55341b44f4e2> in <module>() > 1 #plot(turb_curve_expr.subs(vals), (t, 0, 3600)) > ----> 2 Integral(turb_curve_expr, (t, 0, oo)).subs(vals).doit() > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/integrals.pyc in > doit(self, **hints) > 886 antideriv = None > 887 else: > --> 888 antideriv = self._eval_integral(function, xab[0], > meijerg=meijerg1, risch=risch, conds=conds) > 889 if antideriv is None and meijerg1 is True: > 890 ret = try_meijerg(function, xab) > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/integrals.pyc in > _eval_integral(self, f, x, meijerg, risch, conds) > 1113 # Piecewise antiderivatives need to call special integrate. > 1114 if f.func is Piecewise: > -> 1115 return f._eval_integral(x) > 1116 > 1117 # let's cut it short if `f` does not depend on `x` > > /usr/local/lib/python2.7/dist-packages/sympy/functions/elementary/piecewise.pyc > in _eval_integral(self, x) > 197 def _eval_integral(self, x): > 198 from sympy.integrals import integrate > --> 199 return Piecewise(*[(integrate(e, x), c) for e, c in > self.args]) > 200 > 201 def _eval_interval(self, sym, a, b): > > /usr/local/lib/python2.7/dist-packages/sympy/utilities/decorator.pyc in > threaded_func(expr, *args, **kwargs) > 31 func(expr.rhs, *args, > **kwargs)) > 32 else: > ---> 33 return func(expr, *args, **kwargs) > 34 > 35 return threaded_func > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/integrals.pyc in > integrate(*args, **kwargs) > 1587 > 1588 if isinstance(integral, Integral): > -> 1589 return integral.doit(deep=False, meijerg=meijerg, > conds=conds, risch=risch) > 1590 else: > 1591 return integral > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/integrals.pyc in > doit(self, **hints) > 886 antideriv = None > 887 else: > --> 888 antideriv = self._eval_integral(function, xab[0], > meijerg=meijerg1, risch=risch, conds=conds) > 889 if antideriv is None and meijerg1 is True: > 890 ret = try_meijerg(function, xab) > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/integrals.pyc in > _eval_integral(self, f, x, meijerg, risch, conds) > 1235 try: > 1236 if conds == 'piecewise': > -> 1237 h = heurisch_wrapper(g, x, hints=[]) > 1238 else: > 1239 h = heurisch(g, x, hints=[]) > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/heurisch.pyc in > heurisch_wrapper(f, x, rewrite, hints, mappings, retries, degree_offset, > unnecessary_permutations) > 124 > 125 res = heurisch(f, x, rewrite, hints, mappings, retries, > degree_offset, > --> 126 unnecessary_permutations) > 127 if not isinstance(res, Basic): > 128 return res > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/heurisch.pyc in > heurisch(f, x, rewrite, hints, mappings, retries, degree_offset, > unnecessary_permutations) > 422 > 423 u_split = _splitter(denom) > --> 424 v_split = _splitter(Q) > 425 > 426 polys = list(v_split) + [ u_split[0] ] + special.keys() > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/heurisch.pyc in > _splitter(p) > 399 return (c_split[0], q * c_split[1]) > 400 > --> 401 q_split = _splitter(cancel(q / s)) > 402 > 403 return (c_split[0]*q_split[0]*s, > c_split[1]*q_split[1]) > > /usr/local/lib/python2.7/dist-packages/sympy/integrals/heurisch.pyc in > _splitter(p) > 387 > 388 if _derivation(y) is not S.Zero: > --> 389 c, q = p.as_poly(y).primitive() > 390 > 391 q = q.as_expr() > > AttributeError: 'NoneType' object has no attribute 'primitive' > > > Regards, > > Will > > > On Tuesday, 28 May 2013 15:43:44 UTC+1, Aaron Meurer wrote: >> >> Are you sure you're using the git head? The T(t - (x/V)) in the >> integral is not allowed (we stopped making SymPy objects arbitrarily >> callable). I'm not sure if you meant for that to be a substitution or >> a multiplication, so I didn't try it further. Chances are it's fixed >> in https://github.com/sympy/sympy/pull/2126 though. >> >> Aaron Meurer >> >> On Tue, May 28, 2013 at 9:23 AM, Will Furnass >> <[email protected]> wrote: >> > Hi, >> > >> > I'm fairly new to sympy. I'm trying to evalute an integral analytically >> > over the range 0..oo but when I run the last line in the script below I >> > get >> > the following error (using the sympy git head). >> > >> > CoercionFailed: can't convert DMP([[1], []], ZZ, ZZ[_a1,_b1]) of type >> > <class >> > 'sympy.polys.polyclasses.DMP'> from ZZ[_a1,_b1] to RR >> > >> > Anyone got any ideas as to what this means? >> > >> > Regards, >> > >> > Will Furnass >> > >> > >> > ###### >> > >> > D, dx, k, L, n, P, Q, t, tau_a, tau_s, x= symbols('D dx k, L, n, P, Q, >> > t, >> > \\tau_a, \\tau_s x') >> > >> > V = Q * 4 / (pi * (D**2)) >> > >> > expr1 = (tau_a - tau_s)**n * k >> > expr2 = (t * P * (tau_a - tau_s)**n * n) - (t * P * (tau_a - tau_s)**n) >> > + (k >> > * tau_a) - (k * tau_s) >> > expr3 = 1 / (n-1) >> > expr4 = P * (tau_a - tau_s)**n >> > expr5 = (t * P * (tau_a - tau_s)**n * n) - (t * P * (tau_a - tau_s)**n) >> > + (k >> > * tau_a) - (k * tau_s) >> > expr6 = ((expr1 / expr2) ** expr3) * expr4 / expr5 >> > expr7 = - P * exp(-t * P / k ) * (-tau_a + tau_s) / k >> > expr8 = Piecewise((expr6, Ne(n,1)), (expr7, Eq(n,1))) >> > >> > T = Piecewise((0, t < 0), (k * D * pi * dx * expr8 / Q, t >= 0)) >> > >> > curve_expr = integrate(T(t - (x/V)), (x, 0, L)) >> > >> > vals = { >> > P : 0.00022, >> > k : 0.5, >> > tau_s : 0.01, >> > tau_a : 2.0, >> > Q : 0.01, >> > D : 0.125, >> > L : 1225, >> > n : 3.0, >> > dx : 1} >> > >> > integrate(curve_expr.subs(vals)).eval() >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups >> > "sympy" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> > an >> > email to [email protected]. >> > To post to this group, send email to [email protected]. >> > Visit this group at http://groups.google.com/group/sympy?hl=en-US. >> > For more options, visit https://groups.google.com/groups/opt_out. >> > >> > > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "sympy" group. 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