Subject:
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Re: Off on a tangent (or a sine, anyway)
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Tue, 16 Jan 2001 20:20:39 GMT
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Viewed:
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96 times
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In lugnet.off-topic.geek, A. Mark Wilburn writes:
> If you want a wavelength of 324 and it passes through both points,
> y = 90 cos (1.11 x) + 90 will give you the right equation. (But amplitude is
> now 90, not 120)
Doh! I was trying to be so careful! I thought amplitude was the "height"
from high to low--is it actually half that? At any rate, I meant to write
the min occurs at y=60, so that the high points occur along the line y=180
and the low points occur along y=60. I don't mean to be difficult, but I'm
trying to get it going from (0,180) to (162,60) in a single high:low cycle
(whatever the term).
I've messed around a little further, and the equation:
y=60cos(x/51.5)+120
gets visually pretty close to what I'm looking for. Is there a more logical
method than the try-and-try-again way I've used so far?
I was thinking for some reason that it should be a sine, but cosine works
fine for me, too. Thanks for your help!
Dave!
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Message has 2 Replies:
 | | Re: Off on a tangent (or a sine, anyway)
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| (...) Yep! It's measured from the baseline to a peak (or a valley). (...) <grin> the term for that is half a wavelength, or Crest to Trough. Something like that. (A wavelength is measured from peak to peak, so peak to valley is 1/2 of it). (...) Yes (...) (24 years ago, 16-Jan-01, to lugnet.off-topic.geek)
| | | Re: Off on a tangent (or a sine, anyway)
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| (...) Well, that changes everything, yes. (...) If cos(x/51.5) is close, then you are in radians (Shiri already correctly explained where the 1.11 came from, and she's correct if your wavelength of 324 is in degrees. If it's in radians then you have (...) (24 years ago, 16-Jan-01, to lugnet.off-topic.geek)
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Message is in Reply To:
| | Re: Off on a tangent (or a sine, anyway)
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| (...) I'm a little rusty myself, but there are bits and pieces here that don't quite add up, I think. Having a wavelength of 324 (I'm assuming you mean degrees, although you without stating degrees normally means radians) in which case your sin (...) (24 years ago, 16-Jan-01, to lugnet.off-topic.geek)
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