a newbe question ---- divide inconsistancies between 591 and 592

Thank you This looks like it is what i need.
Will try it soon.
Doug

Doug Stewart wrote:

> Using the code given latter,  I get different results from 5.9.1 and 
> 5.9.2.
> The difference is in the results of the divide function. In 5.9.1 the 
> results are ordered in powers of  "s" which is what you would expect 
> but 5.9.2 does not do this. How do I force 5.9.2 to order the 
> polynomial in power of "s"?
>
> The code works fine in 5.9.1 so thanks to R. Fateman and S. Macrakis 
> for the help.
>
> Doug Stewart
>
> pidmath.mac
>
>
> kill(all);
> globalsolve:true;
> pid:(KD*s^2+KP*s+KI)/s;
> plant:2/(s^2+4*s+3);
> /* plant:64/(s^2+12*s+32); */
>
> /*  make the closed loop equation */
> cl:pid*plant/(1+pid*plant);
> careq1:denom(cl),ratsimp;
>
> /* show the characteristic equation. */
> careq:careq1=0;
>
> /* factor out a real root. */
> q1:divide(careq1,(s+a),s),polysimp;
>
> /* get the quadratic part and the remainder */
> quadr1:part(q1,1);
> rem:part(q1,2);
>
> /* now set the first order root a=(real part of complex roots)  */
> a1:part(quadr1,2)/(2*s),ratsimp;
> a2:a1=a;
>
> /* get the numeric value for a */
> solve(a2,a);
>
> /* now set up the settling time  (set for 1 second)  */
> Ts:1.0;
> Ts1:5/a1=Ts,ratsimp;
> /* solve these two for KD and a   */
> solve([a2,Ts1],[KD , a]),numer;
> /* now choose a damping ratio  (.707)  */
> dr:sqrt(2)/2;
>
> /* these are for debuging only */
> part(quadr1,2);
> part(quadr1,3);
> part(quadr1,4);
>
> eq3:(part(quadr1,3)+part(quadr1,4))=((part(quadr1,2)/s)/(2*dr))^2,ratsimp; 
>
>
> /* now solve these two eq. for KP and KI */
> solve([eq3,rem],[KP,KI]),numer;
> /* show all the results  */
> a;
> KP;
> KI;
> KD;
>
>
>
>
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