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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 9,420 of 10,432    |
|    Nasser M. Abbasi to All    |
|    int( arcsin(x)/x,x), FriCas result    |
|    02 May 17 01:42:07    |
      From: nma@12000.org              Hello;              Why can't Fricas integrate asin(x)/x dx ? Since there is standard       substitution u=asin(x) which converts the integrand to               u*cos(u)/sin(u) du              which Fricas can integrate with no problem?              Illustration using Rubi:              In[88]:= Int[ArcSin[x]/x,x]       Out[88]= -(1/2) I ArcSin[x]^2+ArcSin[x] Log[1-E^(2 I ArcSin[x])]-1/2 I       PolyLog[2,E^(2 I ArcSin[x])]              And now using the transformed version of the integrand:              In[91]:= Int[u*Cos[u]/Sin[u],u]       Out[91]= -((I u^2)/2)+u Log[1-E^(2 I u)]-1/2 I PolyLog[2,E^(2 I u)]              Convert back to x              In[92]:= %/.u->ArcSin[x]//Simplify       Out[92]= -(1/2) I (ArcSin[x] (ArcSin[x]+2 I Log[1-E^(2 I ArcSin[       ])])+PolyLog[2,E^(2 I ArcSin[x])])              we see [92] is same as [88].              But Fricas does not like               ii:=integrate(asin(x)/x,x)              but it can do the transformed version              ii:=integrate(u*cos(u)/sin(u),u)              (u*log((2*sin(u))/(sin(u)+((-1)*(-1)^(1/2)*cos(u)+(-1)*(-1)^(1/2))))+(u*log(        (2*sin(u))/(sin(u)+((-1)^(1/2)*cos(u)+(-1)^(1/2))))+(u*log((2       (-1)^(1/2)*cos(        u)+2*(-1)^(1/2))/(sin(u)+((-1)^(1/2)*cos(u)+(-1)^(1/2))))+(u*       og(((-2)*(-1)^(        1/2)*cos(u)+(-2)*(-1)^(1/2))/(sin(u)+((-1)*(-1)^(1/2)*cos(u)+       -1)*(-1)^(1/2))        ))+((-1)^(1/2)*dilog((2*sin(u))/(sin(u)+((-1)*(-1)^(1/2)*cos(       )+(-1)*(-1)^(1/        2))))+((-1)*(-1)^(1/2)*dilog((2*sin(u))/(sin(u)+((-1)^(1/2)*c       s(u)+(-1)^(1/2)        )))+((-1)*(-1)^(1/2)*dilog((2*(-1)^(1/2)*cos(u)+2*(-1)^(1/2))       (sin(u)+((-1)^(        1/2)*cos(u)+(-1)^(1/2))))+(-1)^(1/2)*dilog(((-2)*(-1)^(1/2)*c       s(u)+(-2)*(-1)^        (1/2))/(sin(u)+((-1)*(-1)^(1/2)*cos(u)+(-1)*(-1)^(1/2)))))))))))/2              Just wondering why, that is all. I am using               FriCAS Computer Algebra System        Version: FriCAS 1.3.0              Thank you,       --Nasser              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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