Entering partial derivatives?

[DrD]

Isn't that interesting? In the beginning of my work with this subject, I did use the template key for this.

In the first post, I was trying to find a way to enter second mixed partials: \(\Large\frac{∂^2f(x,y)}{∂x∂y}\)

After that, I wanted to find ways to evaluate the expression at a point with respect to x, (or y), and we moved away from the template feature. It migrated to the generic entry line forms because (in other cases) the template resulted in the entry line form, anyway: (f(x,y),x)'|{x=1,y=2}, or diff(f(x,y),x)|{x=1,y=2}

This generated the responses up to now. So, armed with "such is the limitation of the where command," "your syntax is ambiguous," because of not knowing when to apply (before/after) expression evaluation for a given point, etc., has resulted in my, mostly irrelevant, opinion of the status quo.

Ironically, I guess I hadn't put the last expression into the template, as you did, and it DOES the evaluation (as you discovered), in the manner in which, -I would think-, it should!

You just never know,( or try to remember), what you're going to get when the same expression entered in various ways, produces various results.

Every now and then, diff(f(x,y),x)|{x=1,y=2} ---> [0 0].
Most other times it triggers ["Invalid | Error: Bad Argument Value"].

In short, I think this is an area in which the software could be improved. I leave it to those empowered to effect change. Fortunately, in my case, I have time to try lots of things, hopefully finding a workable solution.

I enjoy the Prime, and learn along the way! That's a long way to explain the, "why," but that's it. The template key is normally my first go to.

-Dale-