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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 9,183 of 10,432    |
|    Albert Rich to Nasser M. Abbasi    |
|    Re: FriCAS web interface failure    |
|    31 Oct 16 16:59:24    |
      From: Albert_Rich@msn.com              On Saturday, October 29, 2016 at 9:36:13 PM UTC-10, Nasser M. Abbasi wrote:       >       > fyi, Rubi 4.10.1 now gives better answer in terms of only       > elementary functions and no complex numbers to the above       > two problems:       >       > In[6]:= ShowSteps = False;       > In[7]:= Int[(a + b*x)/((3 + x^2)*(1 - x^2)^(1/3)), x]       >       > Out[7]= (a*       > ArcTan[1/       > Sqrt[3] - (2^(2/3)*(1 - x)^(2/3))/(Sqrt[       > 3]*(1 + x)^(1/3))])/(2*2^(2/3)*Sqrt[3]) - (a*       > ArcTan[1/       > Sqrt[3] - (2^(2/3)*(1 + x)^(2/3))/(Sqrt[       > 3]*(1 - x)^(1/3))])/(2*2^(2/3)*Sqrt[3]) +       > (Sqrt[3]*b*       > ArcTan[(1 + 2^(1/3)*(1 - x^2)^(1/3))/Sqrt[3]])/(2*2^(2/3)) - (b*       > Log[3 + x^2])/(4*2^(2/3)) + (a*       > Log[(2 - 2*x)^(1/3) + (1 + x)^(2/3)])/(4*2^(2/3)) - (a*       > Log[(1 - x)^(2/3) + (2 + 2*x)^(1/3)])/(4*2^(2/3)) +       > (3*b*Log[2^(2/3) - (1 - x^2)^(1/3)])/(4*2^(2/3))       >       > In[8]:= Int[(a + b*x)/((3 - x^2)*(1 + x^2)^(1/3)), x]       >       > Out[8]= -((a*       > ArcTan[1/       > Sqrt[3] + (2^(2/3)*(Sqrt[3] -       > x))/(3*(1 + x^2)^(1/3))])/(6*2^(2/3))) + (a*       > ArcTan[1/       > Sqrt[3] + (2^(2/3)*(Sqrt[3] +       > x))/(3*(1 + x^2)^(1/3))])/(6*2^(2/3)) -       > (Sqrt[3]*b*       > ArcTan[(1 + 2^(1/3)*(1 + x^2)^(1/3))/Sqrt[3]])/(2*2^(2/3)) + (b*       > Log[3 - x^2])/(4*2^(2/3)) - (3*b*       > Log[2^(2/3) - (1 + x^2)^(1/3)])/(4*2^(2/3)) -       > (a*Log[-1 - x/Sqrt[3] + 2^(1/3)*(1 + x^2)^(1/3)])/(4*2^(2/3)*       > Sqrt[3]) + (a*       > Log[-1 + x/Sqrt[3] + 2^(1/3)*(1 + x^2)^(1/3)])/(4*2^(2/3)*       > Sqrt[3]) -       > (a*Log[-((Sqrt[3] - x)^3/(3*Sqrt[3])) + 2*(1 + x^2)])/(12*2^(2/3)*       > Sqrt[3]) + (a*       > Log[-((Sqrt[3] + x)^3/(3*Sqrt[3])) + 2*(1 + x^2)])/(12*2^(2/3)*       > Sqrt[3])       >       >       > --Nasser              Yes, the long awaited (at least by me) version 4.10 of Rubi is now available       at http://www.apmaths.uwo.ca/~arich/. As these examples show, Rubi 4.10 does       a much better job at finding optimal antiderivatives of elliptic, and       pseudo-elliptic integrals.              For the integrand in the first example above, when a=1 and b=0,               1/ ((3 + x^2)*(1 - x^2)^(1/3))              Rubi 4.10 returns an elementary antiderivative consisting of two arctan terms       and two log terms; whereas Mathematica 11 returns an Appell hypergeometric       function. But even more interestingly, for the integral of the equivalent       expression               (1 - x^2)^(2/3) / (3 - 2*x^2 - x^4)              where the common divisor has not been canceled, Rubi returns the same       elementary antiderivative; whereas Mathematica indicates it is not even       integrable in closed-form. Maple 2016 is not able to integrate either form of       the integrand.              Albert              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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