Entering partial derivatives?

[DrD]

Thank you for your very informative response, Han!

(Original example): \( f(x,y):=x^2y+xy^2 \)

I seem to have omitted in the group of things I did try, that didn't work, was: diff(f(x,y),x)|{x = 1,y = 2}, which is THE form I expected WOULD work.

The subst() function does work, but somewhat misses the ideal: subst(diff(f(x,y),x),{x = 1,y = 2}) returning 8. Whether that is a "shorthand" means of getting the result, stretches the definition of shorthand a bit.

I'd like to suggest that the authors consider extending the utility value of the "|" where command to include applications like: diff(f(x,y),x)|{x = 1,y = 2}. The context is for the substitution to be applied AFTER the differentiation, as would probably be obvious on inspection in handwritten form.

Again, thanks, I learn a great deal from these responses, and hopefully can share accordingly, as time goes on.

-Dale-