I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this.
'diff(x*y,x) gives the correct result (holds form), while
'diff(x,x) gives 1, calculates the differencial.
I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this.
Problem is in quoted diff, which should not evaluate, but it does in 'diff(x,x) case:
(%i2) 'diff(x*y,x);
d
(%o2) -- (x y)
dx
(%i3) 'diff(x,x);
(%o3) 1
(%i4) 'diff(2*x,x);
d
(%o4) -- (2 x)
dx
'diff(x,x) gives 1 because of simplification in the simplifying function simpderiv.
We have a similar simplification for integrals:
(%i9) 'integrate(1,x);
(%o9) x
Therefore, we can do something like
(%i10) 'diff('integrate(1,x),x);
(%o10) 1
Furthermore, the following simplification is build in:
(%i15) 'diff(x,x,0);
(%o15) x
This works for an arbitrary expression too:
(%i17) 'diff(sin(x),x,0);
(%o17) sin(x)
It might be arguable why Maxima does not do more simplifications of this type, but the implement simplifications are not wrong. I have no example, where these simplifications cause problems.
So, I would suggest not to change the behavior of Maxima to simplify the examples in this bug report.
Setting the status to pending and resolution "works for me".
Dieter Kaiser
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