Comment #6 on issue 1766 by asmeurer: expand(power_base=True) is too aggressive http://code.google.com/p/sympy/issues/detail?id=1766
Here is a slightly modified example that shows that even Maple ignores assumptions on ODEs (Maple is usually a real stickler when it comes to assumptions): > dsolve(diff(f(x), x) = sqrt(f(x)**2*(x + 1))); /2 (3/2)\ f(x) = exp|- (x + 1) | _C1 \3 / > sqrt(f(x)**2); (1/2) / 2\ \f(x) / > int(1/sqrt(x**2), x); x ln(x) --------- (1/2) / 2\ \x / Compare to us (right now): In [16]: dsolve(diff(f(x), x) - sqrt(f(x)**2)*sqrt((x + 1)), f(x)) Out[16]: f(x) ⌠ 3/2 ⎮ 1 2⋅(1 + x) ⎮ ─────── dy = C₁ + ──────────── ⎮ ⎽⎽⎽⎽ 3 ⎮ ╱ 2 ⎮ ╲╱ y ⌡ It seems we can't do that integral, but the point is that Maple just ignores the fact that sqrt(f(x)**2) != f(x) when solving the ODE. -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings -- You received this message because you are subscribed to the Google Groups "sympy-issues" group. To post to this group, send email to sympy-iss...@googlegroups.com. To unsubscribe from this group, send email to sympy-issues+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy-issues?hl=en.