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Topic: strange GCD error from Rubi 4.8, Mathematica 10.1
Replies: 9   Last Post: Sep 24, 2015 10:57 PM

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Nasser Abbasi

Posts: 6,674
Registered: 2/7/05
strange GCD error from Rubi 4.8, Mathematica 10.1
Posted: Sep 12, 2015 3:59 AM
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Fyi,

Mathematica 10.1, on windows 7:

-----------------------
Clear[a, x];
a = 0.3;
solM = Integrate[x/Sqrt[2 a x - x^2], x]
--------------------------

No error and gives a result. But with Rubi 4.8, I get

---------------------------
ShowSteps = False;
Clear[x];
a = 0.3;
solRubi = Int[x/Sqrt[2 a x - x^2], x]
-------------------------------

GCD::exact: Argument 0.6` in GCD[-1,0.6] is not an exact number. >>
General::stop: Further output of GCD::exact will be suppressed during this calculation. >>
Out[88]= -0.3 ArcSin[1-3.33333 x]-Sqrt[((0.6 x)/GCD[-1,0.6]-x^2/GCD[-1,0.6]) GCD[-1,0.6]]

When `a` is made symbolic (or rational number, such as 1/3) then it works:

----------------------
ShowSteps = False;
Clear[x, a];
solRubi = Int[x/Sqrt[2 a x - x^2], x]
---------------------------
No error and gives result.

thanks,
--Nasser





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