CAS.diff command results diff command again

[josephec]

(06-11-2017 12:29 AM)roadrunner Wrote:  The only way I can think of at the moment is to do it in CAS with small x's and then substitute in the big X's, try this from the home screen:

CAS("fx:=SEC(x)+x^2")
CAS("subst(eval(diff(fx,x)),x='X')")

You should get:

(SIN(X)/COS(X)^2)+2*X

-road

Hi Roadrunner,
Thank You so much, WORKS GREAT...
as user enter X and no x, I used:
dfx:=CAS("subst(eval(diff(subst(fx,'X'=x),x)),x='X')");
then dfx will hold the final derivative with X variable to show to user and continue using it in my program
Thanks and have an excellent weekend!
joseph