HP-50g derivatives

[JurgenRo]

(04-03-2017 04:45 AM)Carsen Wrote:  Hi there! I will try to attempt to help you here.

I got the correct answer by doing the following keystrokes in RPN mode...

[ALPHA] S [LS] [X^2] [ ' ] [ALPHA] T [STO>] [ ' ] [ALPHA] T [ENTER] [ENTER] SIN [Right Arrow] [RS] [ ∂ ] <-- (Orange function above the COS key) [RS] [ALG] [EXPAN] <-- (F2 key)

Which gives me COS(S^2)

If you wish to do this in ALG mode, do this...

[LS] [X^2] [ALPHA] S [Right Arrow] [STO>] [ALPHA] [T] [ENTER] [RS] [ALG] [EXPAN]-->(F2 Key) [RS] [ ∂ ] [ALPHA] T [LS] [ () ] SIN [ALPHA] T [ENTER]

[RS] = The orange shift key, [LS] = The white shift key, [ ' ] = The Tick key

In ALG mode, it's essentially the derivative function using the HP 50g's keyboard is inside the Expand function. In RPN mode, just make sure to use the Tick key to make sure the T does not turn into S^2. I get COS(S^2) as a result for both methods. Let me know if there are any questions or confusion on my keystroke examples above. I used the HP 50g 2.15 version so it should work.

Hi Carsen! The methods you are suggesting do give the expected results, thank you very much for this!! But still, I do not understand why

[ALPHA] S [LS] [X^2] [ ' ] [ALPHA] T [STO>] [ ' ] [ALPHA] T [ENTER] [ENTER]
[ ' ][RS] [ ∂ ] [ALPHA] T [LS] [ () ] SIN [ALPHA] T [ENTER] [RS] [ALG] [EXPAN]

does not do the job but expands to 0 (Zero). The only difference (as far as I can figure) is that I used RPN to store S^2 in T and called the derivative on the stack in ALG Fashion, that is by '∂T(sin(T))' [ENTER] [EXPAN]. Shouldn't that give the desired result also?