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Topic: three different results for an integral, which is correct?
Replies: 1   Last Post: Sep 12, 2015 8:39 AM

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Nasser Abbasi

Posts: 6,674
Registered: 2/7/05
three different results for an integral, which is correct?
Posted: Sep 12, 2015 4:08 AM
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Mathematica 10.1, windows 7:

-----------------------------
Clear[a, x];
solM = Integrate[x/Sqrt[2 a x - x^2], x];
solM /. {a -> 0.3, x -> 1}
-------------------------
0. -0.926507 I

Rubi 4.8/Mathematica 10.1:
----------------------
ShowSteps = False;
Clear[x, a];
solRubi = Int[x/Sqrt[2 a x - x^2], x];
solRubi /. {a -> 0.3, x -> 1}
----------------------
-0.942478-1.07975 I

Maple 15.1, windows 7
--------------------
restart;
sol:=int(x/sqrt(2*a*x-x^2),x):
evalf(subs({a=0.3,x=1},sol));
---------------------
-.4712388981-1.079754425*I

Maple and Rubi agree on the complex part but not the real part.
Seems like another brach cut issue?

--Nasser






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