Incorrect extremum

[lrdheat]

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.

[lrdheat]

I think you plotted X+1, not X + COS X

[Ernesto_R]

Hi Spybot!

Your calculator must be in radian mode to plot the graph correctly.

[informach]

Hi!, Spybot:

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

Kind Regards.
informach.

[lrdheat]

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?

[lrdheat]

Spell correct demolished informach's handle! Sorry about that!

[informach]

Hi!, Irdheat:

For your knowledge ...

Kind Regards.

[retoa]

(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.

[lrdheat]

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.

[Tim Wessman]

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.