On Thu, Aug 28, 2008 at 11:36 AM, Ondrej Certik <[EMAIL PROTECTED]> wrote:
>
> On Tue, Aug 5, 2008 at 6:27 AM, Alex Raichev <[EMAIL PROTECTED]> wrote:
>>
>> Hi all:
>>
>> I am having difficulty differentiating a formal symbolic function
>> multiplied by the symbolic constant 1 (see code below). Is this a
>> bug? How can i work around it?
>>
>> Alex
>> =======================================
>> sage:
>> var('x')
>> f= function('F',x)
>> g= x^2
>> a= SR(2)
>> b= SR(1)
>> for j in [f,f*g,f*a,g*b]:
>> print type(j)
>> print diff(j,x)
>>
>> <class 'sage.calculus.calculus.SymbolicFunctionEvaluation'>
>>
>> d
>> -- (F(x))
>> dx
>> <class 'sage.calculus.calculus.SymbolicArithmetic'>
>>
>> 2 d
>> x (-- (F(x))) + 2 x F(x)
>> dx
>> <class 'sage.calculus.calculus.SymbolicArithmetic'>
>>
>> d
>> 2 (-- (F(x)))
>> dx
>> <class 'sage.calculus.calculus.SymbolicArithmetic'>
>> Traceback (most recent call last): print diff(j,x)
>> File "/home/arai021/sage-3.0.2-ubuntu32-intel-i686-Linux/local/lib/
>> python2.5/site-packages/sympy/plotting/", line 3, in <module>
>
>
> ^^^ why is sympy called here?
>
> That's another bug that should be imho fixed, sympy should not be
> called unless needed.
There is a weird bug in Sage (or Python) where in some weird cases it
blames sympy for every single thing that ever goes wrong.
Go figure.
-- William
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