Derivatives on HP 42S
08-21-2018, 01:35 AM
Post: #8
 Thomas Klemm Senior Member Posts: 1,609 Joined: Dec 2013
RE: Derivatives on HP 42S
(08-20-2018 11:54 PM)Albert Chan Wrote:  Why would search for slope of 0 get the maximum ?

Cf. Maxima and minima

We search for a critical point in the interval [14.13,14.14], that is x where f'(x) = 0.

Quote:Should it get the minimum, at x = 14.13 ?

The function is somewhat pathological in that it's close to 0 most of the time and only 1 at the maximum which is where $$\sin(x)=1$$.
That means $$x=\frac{\pi}{2}+k\cdot2\pi$$ for $$k\in\mathbb{Z}$$.

It's not defined (or then takes complex values) where $$\sin(x)<0$$.
Thus the minimal value is 0 when $$x=k\cdot\pi$$ for $$k\in\mathbb{Z}$$.

So the minimal values in that section are $$(4\pi, 0)$$ and $$(5\pi, 0)$$ and the maximal value is $$(\frac{9}{2}\pi, 1)$$.

The flatness of the function makes it hard to numerically find the stationary points.

Cheers
Thomas

Since I used Free42 instead of the HP-42S it could very well be that the results don't agree.
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 Messages In This Thread Derivatives on HP 42S - lrdheat - 08-20-2018, 03:03 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 04:38 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 07:43 AM RE: Derivatives on HP 42S - Albert Chan - 08-20-2018, 11:54 PM RE: Derivatives on HP 42S - lrdheat - 08-20-2018, 10:57 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 11:43 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018, 12:34 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018 01:35 AM RE: Derivatives on HP 42S - lrdheat - 08-21-2018, 02:24 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018, 06:14 AM RE: Derivatives on HP 42S - RMollov - 08-23-2018, 12:58 PM RE: Derivatives on HP 42S - lrdheat - 08-24-2018, 02:51 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-24-2018, 05:52 AM RE: Derivatives on HP 42S - lrdheat - 08-25-2018, 05:19 PM RE: Derivatives on HP 42S - Albert Chan - 08-25-2018, 07:03 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-25-2018, 06:05 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-25-2018, 08:00 PM RE: Derivatives on HP 42S - Albert Chan - 08-25-2018, 09:20 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-26-2018, 04:54 AM RE: Derivatives on HP 42S - Thomas Okken - 08-26-2018, 01:54 PM RE: Derivatives on HP 42S - lrdheat - 08-26-2018, 04:47 PM RE: Derivatives on HP 42S - Albert Chan - 08-26-2018, 08:39 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-26-2018, 08:00 PM RE: Derivatives on HP 42S - Albert Chan - 08-29-2018, 01:52 PM

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