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Submitted by : (unknown) at: 2007-11-17T22:08:37-08:00 (9 years ago)
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Consider the following two expressions:

fricas
exa:=integrate(log(1/x)/x^a,x)

\label{eq1}-{{x \ {\log \left({1 \over x}\right)}}\over{{\left(a - 1 \right)}\ {{e}^{-{a \ {\log \left({1 \over x}\right)}}}}}}(1)
Type: Union(Expression(Integer),...)
fricas
exb:=integrate(log(1/x)*x^b,x)

\label{eq2}{x \ {\log \left({1 \over x}\right)}\ {{e}^{-{b \ {\log \left({1 \over x}\right)}}}}}\over{b + 1}(2)
Type: Union(Expression(Integer),...)

which are equivalent by setting a=-b. However, the operation limit doesn't like both equally well:

fricas
limit(exa,x=0)
>> Error detected within library code: can not determine sign

fricas
limit(exb,x=0)
>> Error detected within library code: can not determine sign

Martin

Now they both fail, as they should.

Status: open => fixed somewhere




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