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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 9,646 of 10,432    |
|    Albert Rich to Albert Rich    |
|    Re: fyi, new build of CAS integration te    |
|    04 Oct 17 04:56:07    |
      From: Albert_Rich@msn.com              On Tuesday, October 3, 2017 at 5:58:21 PM UTC-10, Albert Rich wrote:              > However, there may still remain a problem. For the pseudo-elliptic       integrand 1/((2-x^2)*(x^2-1)^(1/4)), Rubi returns       >        > ArcTan[x/(Sqrt[2]*(x^2-1)^(1/4))]/(2*Sqrt[2]) +        > ArcTanh[x/(Sqrt[2]*(x^2-1)^(1/4))]/(2*Sqrt[2])       >        > which is never real on the real line, although the integrand is when x^2>1.        This is analogous to the way log(x) is not real when x<0, although 1/x is real       on the entire real line. So is the above antiderivative for 1/(       2-x^2)*(x^2-1)^(1/4)) optimal        in terms of reality?       >        > Albert              Converting the above arctanh term to a log you get                ArcTan[x/(Sqrt[2]*(x^2-1)^(1/4))] / (2*Sqrt[2]) +         Log[(Sqrt[2]*x+2*(x^2-1)^(1/4))/        (Sqrt[2]*x-2*(x^2-1)^(1/4))] / (4*Sqrt[2])              for the antiderivative of 1/((2-x^2)*(x^2-1)^(1/4)), which magically is real       in all the right places and hence optimal.              Albert              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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