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20-Turquoise

## Plotting local max-min-points ?

Hello Everyone.

From :

Plotting local max-min-points ?

Regards.

1 ACCEPTED SOLUTION

Accepted Solutions
24-Ruby V
(To:lvl107)

@lvl107 wrote:

Could you attach *.xmcd ? ( I'm afraid I may hit wrong key stroke... )

Best Regards.

Hmm, really!??

Here's a slightly different approach:

Unfortunately the more direct and logical

does not work in Mathcad - muPad is not capable to find the solutions.

9 REPLIES 9
21-Topaz I
(To:lvl107)

Hi,

Set a function that is the derivative of f(x).

Use the root function on this derivative within a range to determine unique roots.

You now have enough info to plot the points.

24-Ruby IV
(To:lvl107)

May be like thi

20-Turquoise
(To:ValeryOchkov)

Many thanks both of you, Valery. And I still have a query : "How to prove what point is local min-point ?

Best Regards.

24-Ruby V
(To:lvl107)

20-Turquoise
(To:Werner_E)

Could you attach *.xmcd ? ( I'm afraid I may hit wrong key stroke... )

Best Regards.

23-Emerald I
(To:lvl107)

AWWW!  C'mon!

24-Ruby V
(To:lvl107)

@lvl107 wrote:

Could you attach *.xmcd ? ( I'm afraid I may hit wrong key stroke... )

Best Regards.

Hmm, really!??

Here's a slightly different approach:

Unfortunately the more direct and logical

does not work in Mathcad - muPad is not capable to find the solutions.

23-Emerald I
(To:lvl107)

Some basic calculus (see Werner's application):

• First derivatives of a function are zero at inflection points (maxima/minima),
• The sign of the second derivative at the inflection point indicates minima (second derivative positive) or maxima (second derivative negative.)
24-Ruby V
(To:lvl107)

In case of this function Mathcads symbolics is capable enough to give you al solutions, so you should use it.

If your goal is to limit the results to x1<x<x2 you may use the "assume" modifier.

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