higher derivatives of implicit equation?

09162017, 11:33 AM
(This post was last modified: 09162017 05:20 PM by DrD.)
Post: #1




higher derivatives of implicit equation?
Can higher order derivatives be obtained in CAS, (without programming)?
Example: z:=(3*x^2y^2) = 16, simplify(implicit_diff(z,x,y)) leads to 3*x /y as the first derivative of z. How would one obtain the (Second derivative): d^2y/dx^2=(3*y3*x*3*x/y)/y^2 (or simplified equivalent)? Dale 

09162017, 05:52 PM
Post: #2




RE: higher derivatives of implicit equation?
simplify(implicit_diff(z,x,y,2)) works for me on the latest version. So next update (if any) should have it being very simple at least.
TW Although I work for HP, the views and opinions I post here are my own. 

09162017, 07:13 PM
Post: #3




RE: higher derivatives of implicit equation?
Thank you kind sir. (I should have thought to try that!)
Dale 

09182017, 10:00 AM
Post: #4




RE: higher derivatives of implicit equation?
I have tried that on my Prime with software 2017 07 10 (12066) and cas 1.1.211
and the command implicit_diff(z,x,y,2) gace Error Bad Argument Value 

09182017, 09:17 PM
(This post was last modified: 09182017 09:21 PM by Helge Gabert.)
Post: #5




RE: higher derivatives of implicit equation?
Yes, we mere mortals will have to wait for the next firmware update (if any!) . . . maybe more XCAS commands will be implemented as well, as discussed here
http://www.hpmuseum.org/forum/thread857...light=xcas 

09192017, 06:04 AM
(This post was last modified: 09212017 12:37 PM by parisse.)
Post: #6




RE: higher derivatives of implicit equation?
In the meantime, you can enter this program:
Code:


09202017, 02:32 PM
Post: #7




RE: higher derivatives of implicit equation?
Great! Just two minor modifications. In order to run on the Prime current firmware,
1) n=1 in the first line gives an error message "unable to eval test in loop . . . " and ought to be replaced by n 2) eq should not be entered as an equation, but as an expression, in order to avoid the =undef 

09212017, 12:38 PM
Post: #8




RE: higher derivatives of implicit equation?
I have edited the n=1 (default argument not available in current firmware).


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