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Incorrect extremum
05-01-2016, 09:21 PM
Post: #1
Incorrect extremum
On calculator with 10077, I plotted X+ Cos X

When choosing extremum on the graph plot, it incorrectly identifies inflection points where f'(X) , f''(X) both =0 as extremums.
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05-01-2016, 10:02 PM
Post: #2
RE: Incorrect extremum
I think you plotted X+1, not X + COS X
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05-01-2016, 10:31 PM
Post: #3
RE: Incorrect extremum
Hi Spybot!

Your calculator must be in radian mode to plot the graph correctly.
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05-02-2016, 02:06 AM (This post was last modified: 05-02-2016 02:07 AM by informach.)
Post: #4
RE: Incorrect extremum
Hi!, Spybot:

In one point, of coordinates, not have minimum and maximum, in extremum (indicated with cross), in the plot image.

Kind Regards.
informach.


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05-02-2016, 03:11 AM
Post: #5
RE: Incorrect extremum
Hello informs have and spybot,

On informach's plot, it shows no maximum or minimum found...on my Prime and on my iPad emulator, the inflection points are incorrectly found as extremums.

Why am I getting the results misanalyzed on my units?
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05-02-2016, 03:13 AM
Post: #6
RE: Incorrect extremum
Spell correct demolished informach's handle! Sorry about that!
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05-02-2016, 12:36 PM
Post: #7
RE: Incorrect extremum
Hi!, Irdheat:

For your knowledge ...

Kind Regards.


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05-02-2016, 01:23 PM
Post: #8
RE: Incorrect extremum
(05-01-2016 09:21 PM)lrdheat Wrote:  On calculator with 10077, I plotted X+ Cos X

When choosing extremum on the graph plot, it incorrectly identifies inflection points where f'(X) , f''(X) both =0 as extremums.

You are right, but I don't find it bad, as there is no menu function to find the inflection points.
Extremum will find both extrema and inflection points.
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05-02-2016, 03:07 PM
Post: #9
RE: Incorrect extremum
I disagree...an inflection should not be analyzed as an extremum. If an inflection is suspected, one can plot in the advanced graphing app, check for inflection, and confirm with second derivative.
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05-02-2016, 04:21 PM
Post: #10
RE: Incorrect extremum
Its kind of a legacy from the older HP root finder. You'll notice that the 50G behaves in an identical way. It is definitely something that we'd like to change or improve at some point though because it can be confusing as pointed out.

TW

Although I work for the HP calculator group, the views and opinions I post here are my own.
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