tellsimp tells me that defining rules on + and * might not work. And in fact I was not lucky
with it. So I decided to learn how the simplifier works. But hacking simplus and friends is
really a hard job. It is more or less impossible to trace these functions in simp.lisp cause
they work with lots of side effects on the passed in arguments (rplaca and rplacd).
What I have done so far (in my private copy of simp.lisp - I do not plan to commit to
simp.lisp at this very experimental state) is
v: vector(1,2);
v - v; --> vector(0,0)
0 * v; --> vector(0,0)
v + v; --> 2 * vector(1,2) is already done by builtin simplifications.
w: vector(3,4);
v + w; --> v + w no builtin simplification; so I am free to define my own, which is not very
difficult then
Generally I do not plan do create builtin simplifications for vectors. For better readability
vector expressions should only be nicely displayed when typed in and only be simplified if
the user asks explicitely for it. An explicit function should do the work.
I think the next important step - and that is why I posted to the list this evening - is to make
clear what simplification rules I (we) want. I believe that following Robert's suggestion to
take mathematics as a guideline would be a good thing.
Volker
Am 15 Nov 2008 um 16:36 hat Barton Willis geschrieben:
> Do you have a plan for how to do vector addition (tellsimp, hack
> simplus, ...)?
>
> Barton
>
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