Extremums on Graph

[lrdheat]

Curious as to why some functions in the graphing app will not find an extremum, even though one is found in solve in the CAS environment. The 2nd derivative of (e^2*x)*sin(3*x) is an example.

[roadrunner]

Assuming you are talking about the advanced graphing app, I had no trouble finding extremum. Just select from the menu: Trace/Poi/Vertical Extrema, then touch on the plot near the extrema you want.

   
   

-road

[lrdheat]

I was in regular function graphing app...

[Carsen]

I was able to find multiple extremums on the 2nd derivative of (e^2*x)*sin(3*x) in the Function App. Everything worked as expected. The 2nd derivative was solved in the HOME environment in RPN mode & put in the Function app. Then plotted.

I used my G1 HP Prime with the 20181016 firmware (not the latest).

We may need to provide further details in order to figure out what's going on.

[lrdheat]

What is odd is that I can put the function in regular graph app in, say, F1(X), and d(d(F1(X))) in F2(X), and it plots. Finds roots but not extremums. I can’t seem to get the same procedure to work in advanced graph app.

[Carsen]

Ahhh. I get it. You used the derivative template to calculate the 2nd derivative of (e^2*x)*sin(3*x) in the function app itself. When I did that, I was able to replicate your example.

Good question. Unfortunately, I don't know why it behaves this way.

[jte]

(01-25-2020 09:52 PM)lrdheat Wrote:  What is odd is that I can put the function in regular graph app in, say, F1(X), and d(d(F1(X))) in F2(X), and it plots. Finds roots but not extremums.

Is this still happening for you? I just tried it in 2.1.14592 (2021 06 09) and jumped to a bunch of extrema, via Fcn / Extremum in a Plot view.

(01-25-2020 09:52 PM)lrdheat Wrote:  I can’t seem to get the same procedure to work in advanced graph app.

The Advanced Graphing app doesn't currently handle expressions involving derivatives; the current workaround is to differentiate symbolically using the CAS and then put the result into the Advanced Graphing app.

[lrdheat]

Yes! It works now, using the template!