Greetings everyone.
I'm a new HP convert, I'm moving from a TI-84 to an HP 50G in anticipation for college. However, I still need to finish High School Calculus. On the TI-84 one could put a function in parametric or polar form and on the "calc" menu find the value, dy/dx, dr/d0, dx/dt, or dy/dt, at any point in the window? Is there a way to do this on 50G? Looking at a friends TI-89, I see they have this function, but this capability is only available with functions on the 50G. Help!

Not on the graph, I think you have do this from the home screen.

Hi Ben, I was a TI-82 user until a few years ago, so I know where you're coming from. What you describe on the TI 8x series is a real convenience, but that kind of specialization makes the your TI a much less flexible tool.

I use my 50g in RPN mode with soft menus. I store information in a directory structure similar to a personal computer. I have directories like MATH, PHYS, etc and each has subdirectories based on chapters and sections down to individual problems. This allows me to store the plot, equations, derivatives, matrices, and nearly anything else for any particular problem all together in one place. Yes, I can carry my homework around on my calculator. I use the Archive command to back it all up.

Ok, so what does all that have to do with your question? It puts the lack of a corresponding function on your HP 50g into perspective. On your HP, you can compute derivatives symbolically, store the result, and then recall the result to the stack and use the SUBST (substitute) function in the ALG menu to plug in a numerical value (or a list of numerical values!) on the stack or you can plot the derivative and look up values in the table. Use the variable EQ to store an expression to plot. You can also plug your own values into the independent variable on the table if you select "Build Your Own" in the TBLSET screen under Type. Note that you can even store the table you produce! So it's a different approach and it takes some practice, but it's much more profitable in the long run. Programming can make a lot of this happen with a few button presses.

Have fun and make sure you download the training aids at
http://h20331.www2.hp.com/Hpsub/cache/383680-0-0-225-121.html

You should also check out the
comp.sys.hp48 newsgroup where there is scads of information similar to what you're looking for.