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Topic: A bug in Rubi 2
Replies: 5   Last Post: Oct 10, 2011 4:14 PM

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Posts: 1,245
Registered: 4/26/08
A bug in Rubi 2
Posted: Oct 7, 2011 1:12 PM
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I was looking into elementary antiderivatives for the eight algebraic
integrands listed in a recent post and noticed that the following rule
in Rubi 2 needs a factor 1/a in the evaluation:

Int[1/((a_.+b_.*x_^2)*Sqrt[c_+d_.*x_^2]),x_Symbol] :=
x/Sqrt[c+d*x^2] /;
FreeQ[{a,b,c,d},x] && ZeroQ[a*d-b*c]

For a=c=0, the evaluation should be -1/(2*b*x*Sqrt[d*x^2]).

I suggest to replace this rule by a conversion of the exponents (-1,n)
into (0,n-1), which produces a factor d/b, and to finish with rules for
a single quadratic binomial.


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