Derivatives

09282022, 12:53 PM
Post: #1




Derivatives
Any best practices when dealing with numerical first and second derivatives? The diff command is iffy at best in HP Prime PPL nonCAS.
Also, I working on being more comfortable with the CAS mode and make it my primary mode when I am working with the Prime. 

09292022, 12:51 PM
(This post was last modified: 09292022 01:09 PM by Arno K.)
Post: #2




RE: Derivatives
Hello Eddie,
diff and  (where) seem not to work, doesn't matter how many brackets are used as this is translated to ', that is (diff(x^3))x=5 provides diff(125,5). You can use '(∂(x^3,x)(x = 5))' which then provides the numeric result. Arno edit: diff(e^(2*x)+5*x^3x,x,2,x=2) provides 60+2*e^2, that does the trick for higher derivatives 

10022022, 12:47 AM
Post: #3




RE: Derivatives
Trying the second derivative in a program:
Code: EXPORT DER2(f,v,n) Home: DER2(X^3,X,1) > Error: Bad argument value ("diff(f,v,2,v=n)")] DER2('X^3','X',1) > diff(diff(3.006003,2),0) CAS: DER2(X^3,X,1) > Error: Bad argument value ("diff(f,v,2,v=n)")] DER2(x^3,x,1) > diff(diff(3*x^2,2),0) I hope that the next Prime update will allow for numerical differentiation for both first and second derivatives. 

10022022, 03:11 PM
Post: #4




RE: Derivatives
(10022022 12:47 AM)Eddie W. Shore Wrote: Trying the second derivative in a program: Hello, try using this little program: Code:
Example: DER2 (function, degree of derivation, number) DER (t ^ 3,2,4) > 24 Sincerely, robmio 

10022022, 04:37 PM
Post: #5




RE: Derivatives
(10022022 12:47 AM)Eddie W. Shore Wrote: Trying the second derivative in a program: another program uses the limits of the function: Code:
grado > degree of derivation num > value of the derivative ds = 1 > left limit ds = +1 > right limit ds = 0 > bidirectional limit examples: DER2((t)>t^3,2,4,0) > 24 DER2((x)>Si(x),1,0,0) > 1 DER2((x)>ln(x),1,0,1) > +inf DER2((x)>ln(x),1,0,1) > inf DER2((x)>ln(x),1,0,) > +/inf DER2((t)>e^(2*t),3,7,0) > 8*exp(14) 

10042022, 01:47 PM
Post: #6




RE: Derivatives
Ma program is smaller and insists in x being used:
#cas dif2(f,gr,val):= BEGIN return diff(f,x,gr,x=val); END; #end and does the job. Arno 

10052022, 09:44 AM
Post: #7




RE: Derivatives  
10052022, 09:52 AM
Post: #8




RE: Derivatives  
10052022, 04:21 PM
Post: #9




RE: Derivatives
Perhaps because dif2(Si(x),1,a) provides sin(a)/a and then 0 is used for a, without bothering with limits.
Arno 

10062022, 04:55 AM
Post: #10




RE: Derivatives  
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