 How to evaluate f'' at a specific point? - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: How to evaluate f'' at a specific point? (/thread-3945.html) How to evaluate f'' at a specific point? - lrdheat - 05-22-2015 05:49 PM Dumb question...how in home or CAS do I enter f''(3 root (x-2)) where x=some number of interest? RE: How to evaluate f'' at a specific point? - DrD - 05-22-2015 06:46 PM Did you try: (x-2)^(1/3)'' or: ∂((x-2)^(1/3),x)' RE: How to evaluate f'' at a specific point? - lrdheat - 05-22-2015 07:20 PM In trying to get the second derivative at a specified point, I'm having difficulty in accessing the proper syntax. The template gives me d/dx. I can then get, say, ((d 3 root x-2 / dx)/dx))|x=1.99. This returns 0 instead of 478+. What am I doing wrong? RE: How to evaluate f'' at a specific point? - Helge Gabert - 05-22-2015 08:42 PM I would just do diff(diff(3ROOT(x-2),x),x) and then Ans|x=1.99 (Ans actually has to be copied explicitly from the command line above) returns 478.76 . . . for me. Or do you have to do it with the d/dx template? [You can also define f(x):=3Root(x-2), and then simply type f''(1.99) also returns 478.76 . . .] RE: How to evaluate f'' at a specific point? - lrdheat - 05-22-2015 09:03 PM That works (thanks!). Seems like there should be a more direct way to do this. RE: How to evaluate f'' at a specific point? - toshk - 05-22-2015 09:50 PM (∂(∂((x-2)^(1/3),x),x)|(x )= 1.99) Credit: Eddie's Math and Calculator Blog series, by Edward Shore 3.24. RE: How to evaluate f'' at a specific point? - parisse - 05-23-2015 05:49 AM More natural syntax: f(x):=(2-x)^(1/3); f''(1.99) For a large number of derivatives, for example 5, run diff(f(x),x,5)(x=1.99) RE: How to evaluate f'' at a specific point? - lrdheat - 05-23-2015 04:11 PM Thanks...this is what I hoped for! And when using the n root entry, negative results are produced for this equation directly as opposed to a complex number result! RE: How to evaluate f'' at a specific point? - lrdheat - 05-23-2015 04:19 PM Can this syntax be used in the function graphing app...the diff(f(x),x,2) form? What is the proper syntax for this?