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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 8,945 of 10,432    |
|    Nasser M. Abbasi to All    |
|    if result of dsolve contains integral, w    |
|    06 Jan 16 01:22:02    |
      From: nma@12000.org              If one has a separable ode, first order, such as this:              eq:= diff(y(x),x) = (a4*x^4+a3*x^3+a2*x^2+a1*x+a0)^(-1/2);              Maple gives the answer with simply integrating the RHS, but       leaves the integral unevaluated. Would you consider this as solved       or not? Here is Maple solution to the above ode               result:= y(x) = Int(1/sqrt(a4*x^4+a3*x^3+a2*x^2+a1*x+a0), x)+_C1              The answer is of course correct from math point of view,       and it passes the test:               r := odetest( result,eq );              But if the integral is not actually solved, should one consider       this as valid solution to an ode? This means all ode's of the form       y'(x) = f(x) can be considered solved, by just adding an integral to       RHS and a constant, even if the CAS can't solve the integral.              Mathematica gives this              DSolve[-(1/Sqrt[a0 + a1*x + a2*x^2 + a3*x^3 + a4*x^4])+ y'[x] == 0, y[x], x]              y[x] -> C[1] - (2 EllipticF[        ArcSin[Sqrt[(((x -        Root[a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 1]) (Root[        a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 2] -        Root[a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 4]))/((x -        Root[a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 2]) (Root[        a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 1] -        Root[a0 + a1 #1 + a2 #1^2 + a3 #1^3 + a4 #1^4 &, 4])))]       ..... too long to show....                     I was just wondering what is the view on this. Would you consider       this as "solved" or not? I am updating my Kamke ODE tests, and       needed to make sure I grade Maple as pass for this or no.              --Nasser              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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