Teaching maxima a new identity



Macrakis wrote:

>
>  I don't have time to look at the details, but did you try 
> ratsimp(expr),algebraic:true (with the tellrat in force) on the result?


I have been trying to learn Maxima for some time now and I have a few 
observations I would like to pass on.
1) The learning curve for simplification is way too steep.
    Maxima must be improved in this area. Here is an example:
While trying to write a batch file to explicitly factor a 3rd order 
polynomial into its 1st and 2nd order parts, I gave the program a known 
set of numerical values just to see if I had made any typos yet. The 
answer was not what I was expecting so I went through the code but could 
find no fault there. So to make a long story short, after much time I 
found  that the answer  was just a long way of saying 0.
Here it is:

(%i28) EV(a9,NUMER)
(%o28) 
0.03703703703704*(0.57735026918963*(-1)^0.16666666666667*(27.0*(-%I)^0.66666666666667-27)
            -31.1769145362398*(-%I)^0.33333333333333)
(%i29) EV(a9,RATSIMP)
(%o29) 0
(%i30) EV(REALPART(a9),NUMER)
(%o30) -1.0
(%i31) EV(IMAGPART(a9),NUMER)
(%o31) -1.732050807568877

Now I don't know what to believe!!!!!

Now I find out there is also a  " ratsimp(expr),algebraic:true (with the 
tellrat in force)" combinations!!!! ( from above)
When I look at: describe(simp) and start reading through all the options 
there, I just give up!! After many hours of trying to factor a 3rd order 
int a 1st and second order I give up. I did this in basic and in "C" and 
in pascal and could do it in Fortran and Fourth and in Z80 68HC11 6809 
etc, but not in Maxima.
When you get it working I will try it again.

Doug Stewart B.E.Sc. P.Eng.