Derivating problems

08222018, 05:53 PM
Post: #1




Derivating problems
Hi world, I'm starting using this hp prime v2. But, I've got a problem with this when trying to get partial derivatives or just one variablederivative.
For example: when I type "diff(x^26*xy^2+y^2+10*y+18,X)", it just shows: 2x, taking Y as 0, what I want is to know what is wrong with my calculator or some settings I've chosen before. 

08222018, 09:46 PM
Post: #2




RE: Derivating problems
(08222018 05:53 PM)kjpuma Wrote: Hi world, I'm starting using this hp prime v2. But, I've got a problem with this when trying to get partial derivatives or just one variablederivative. There are several problems with your command. 1. xy is different from x*y  always be explicit with your operators as no software will be able to tell the difference between the mathematical product \( xy \) from the variable name \( xy \) without explicit operators. 2. You used a mixture of 'x' and 'X' for your variables. They are necessarily different. Moreover, the 'X' variable is a system variable whose content is always a real number (which may cause issues with symbolic manipulation). 3. Make sure you are using the CAS view and make sure that nothing is stored in the variables you are using. In your case, if you stick to using 'x' and 'y' (lowercase) then you can "delete" them using: purge([x,y]) in the CAS view. Graph 3D  QPI  SolveSys 

08232018, 08:39 AM
Post: #3




RE: Derivating problems
(08222018 05:53 PM)kjpuma Wrote: Hi world, I'm starting using this hp prime v2. But, I've got a problem with this when trying to get partial derivatives or just one variablederivative. image share online Best, Aries 

08232018, 09:17 AM
Post: #4




RE: Derivating problems
Frankly Aries, I don’t understand why you keep posting (big) TI nSpire screen shots in Prime threads. It doesn’t help the OP to solve his issue and doesn’t provide any added value.
It would have been much more useful if you have provided some explanation about how to work with the Prime or posted a Prime screen shot such as this one: 

09212018, 10:12 PM
Post: #5




RE: Derivating problems
Hello Community,
well, I am running into the same problem, and after research on the net, I found an old thread here in the forum that looked promising...but I ran into trouble and ended up in this thread. What I've been looking for is to get the second derivative of a function. Sadly, I can't get it done. As I understand, the only way to do this on the Prime is, to enter: diff(f(x),$(x,2)) or, what seems the same: diff(f(x),x$2). Both Versions return a 0, which is not correct. diff(f(x),x) works fine, so does f', f'' and so on. I made sure, that I'm in CAS mode, and that the variables x is not in use. btw.. f(x):=1/x^5 Thank's in advance for any suggestions, corrections or help 

09222018, 10:18 AM
Post: #6




RE: Derivating problems  
09222018, 10:32 AM
Post: #7




RE: Derivating problems
Thank you roadrunner,
so, as I got it now, diff works with expressions only, not with functions? I got quite confused, because of the old thread that stated: diff(f(x),x$2 which is to me a function. 

09222018, 10:33 AM
Post: #8




RE: Derivating problems
of course not, this man don't know Tiplanet web site !!!
Peccato. Gérard. 

09222018, 02:35 PM
Post: #9




RE: Derivating problems
(08232018 09:17 AM)Didier Lachieze Wrote: Frankly Aries, I don’t understand why you keep posting (big) TI nSpire screen shots in Prime threads. It doesn’t help the OP to solve his issue and doesn’t provide any added value. I think that the moderators are NOT doing their job 

09222018, 05:02 PM
Post: #10




RE: Derivating problems
Hi Wheazel:
(09222018 10:32 AM)wheazel Wrote: Thank you roadrunner, diff() should work with expressions and functions. In other words, it should work regardless if the user stores it in 'f' or 'f(x)'. (09212018 10:12 PM)wheazel Wrote: diff(f(x),$(x,2)) or, what seems the same: diff(f(x),x$2). Both Versions return a 0, which is not correct. diff(f(x),x), f', and f'' are all some of the correct ways to differentiate the expression/function. May I ask why you are using diff(f(x),$(x,2)) or diff(f(x),x$2)? I've never seen this syntax for a HP Prime ever. The '$' is very confusing. Did you use the [HELP] key on the HP Prime in the upper left part of the keyboard? To use the [HELP] key on diff(), select diff() from the Calculus menu in the CAS portion of the toolbox and put it on the Entry Line. Then simply press the [HELP] key. You can see the syntax, a description, and examples. Check it out. It should clear up syntax issues, especially with the examples. Let me know how everything works out! 

« Next Oldest  Next Newest »

User(s) browsing this thread: