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HP-50g derivatives
04-04-2017, 03:41 AM
Post: #4
RE: HP-50g derivatives
Make sure that in RPN mode, put the variable T onto the stack by pressing the [ ' ] key first and then [ALPHA] [T] [ENTER]. This is the key to this entire problem because it puts the letter T onto the stack without turning into the S^2. Now you can press the [SIN] key and it should say SIN(T) on level 1. Then, put the variable T on the stack again with the same process, press the [ ' ] key and then press [ALPHA] [T] [ENTER]. Now all you need to do is execute DERIV or ∂ function above the [COS] key to derive the function, which gives you COS(T). Then use the EXPAN function to transform the answer COS(T) into COS(S^2).

For ALG mode, I have tried to attached a picture that has the steps I used to get my answer but I couldn't. It said that my file was too big. So I will have to explain it with words again. Notice how the EXPAN function is around the derivative so that it looks like this BEFORE pressing enter...


That's the key to getting this to work. I have tried doing the exact same command without the EXPAND function around the derivative but it did not work. I got the answer 0. You - for some odd reason - NEED the derivative function inside the EXPAND function.

You also need to use the derivative function that is on the [COS] key when using ALG mode. It's the shifted orange function that looks like this...

Are you doing that? Do you know how? I have tried to use the DERIV function inside the expand function but it does not work. You need to also use the derivative function that is shifted on the [COS] key.

Any confusion? Any more questions? Please ask! I am definitely not an expert of this machine so explaining why the derivative needs to be inside the expand function is beyond my knowledge. I had the same problem with my limit problems except it said "Error: Non algebraic in expression".So I figured out that I needed to have my limit inside the EXPAN function in order to get an answer and it worked. I have only owned this machine for about 6 months now.

Although, my guess is that ALG mode is somewhat incomplete and that's why the EXPAN function is needed. I don't really know though. Anyway, I hope this gets you the explanation you need.
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Messages In This Thread
HP-50g derivatives - JurgenRo - 04-02-2017, 07:03 PM
RE: HP-50g derivatives - Carsen - 04-03-2017, 04:45 AM
RE: HP-50g derivatives - JurgenRo - 04-03-2017, 07:18 PM
RE: HP-50g derivatives - Carsen - 04-04-2017 03:41 AM
RE: HP-50g derivatives - JurgenRo - 04-04-2017, 07:33 PM
RE: HP-50g derivatives - Carsen - 04-04-2017, 08:42 PM
RE: HP-50g derivatives - JurgenRo - 04-04-2017, 09:26 PM
RE: HP-50g derivatives - Carsen - 04-06-2017, 08:32 PM
RE: HP-50g derivatives - JurgenRo - 04-07-2017, 11:19 PM

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