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Calculator Tech Support =>
Technology & Calculator Open Topic
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tyskis
Member
Joined: 20 Nov 2003
Posts: 238
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 Posted: 04 Mar 2004 09:56:55 am Post subject: |
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I have a strange sincurve here on my calc:
try Y1=sin(X
Xmin = 0
Xmax = 720
Xscl = 90
Ymin = -2
Ymax = 2
Yscl = 1
Xres = 1
now look at the graph. looks rather normal, doesn't it?
Now change the Xmax to 1440. This makes the periods of the curve become more tight. So long everything right.
Now change the Xmax to 2880. This makes the periods of the curve become LESS tight. strange isn't it? shouldn't they become even more tight, and become just a broad black band over the screen? Or am i Wrong? My math-teacher suggested it was something that TI had programmed in to avoid a black screen, but that sound not useful at all...
Any good suggestions?  |
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Jeremiah Walgren
General Operations Director
Know-It-All
Joined: 24 May 2003
Posts: 1937
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| Posted: 04 Mar 2004 12:35:28 pm Post subject: |
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| Did you just discover this through trying to entertain yourself, or is it for an actual problem? I don't know why it'd do that though... |
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Darth Android
DragonOS Dev Team
Bandwidth Hog
Joined: 31 May 2003
Posts: 2104
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| Posted: 04 Mar 2004 01:14:07 pm Post subject: |
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| im pinpointing it, the change occurs between 1600 and 1700 of Xmax |
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Ray Kremer
Member
Joined: 16 Feb 2004
Posts: 237
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| Posted: 04 Mar 2004 02:44:36 pm Post subject: |
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I can't duplicate that in degrees mode. Are you in radians mode? That would be rather silly given the period of the sine curve would then be 2pi, which is less than the distance between each plotted pixel with a window like that.
Try this, in degree mode, on a 83 family model:
y1=sin(x)
y2=cos(x)
xmin=-16920
xmax=16920
xscl=1440
ymin=-2
ymax=2
yscl=1
xres=1 |
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X1011
10100111001
Active Member
Joined: 14 Nov 2003
Posts: 657
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| Posted: 04 Mar 2004 03:46:14 pm Post subject: |
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tyskis wrote: Now change the Xmax to 2880. This makes the periods of the curve become LESS tight. strange isn't it? shouldn't they become even more tight, and become just a broad black band over the screen? Or am i Wrong?
It is due to the inaccuracy of the graphing at large window settings. every pixel covers a couple of waves, so it doesn't get calculated exact enough to represent the real waves. try setting Xmax to 1440 and Xres to 2, you will get a similar effect, but when you change Xres to 1, it will be different.
Last edited by Guest on 04 Mar 2004 03:47:30 pm; edited 1 time in total |
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CoBB
Active Member
Joined: 30 Jun 2003
Posts: 720
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| Posted: 04 Mar 2004 04:59:50 pm Post subject: |
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| It comes from the way TI draws graphs. For every pixel column only one value is calculated and plotted. So if every pixel coincides with the same phase in the sine curve, you'll get a nice horizontal line. Set Xmin and Xmax to A and 188*pi+A respectively, and you'll see. A can be anything. |
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X1011
10100111001
Active Member
Joined: 14 Nov 2003
Posts: 657
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| Posted: 04 Mar 2004 06:43:24 pm Post subject: |
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| Try 378*pi for Xmax, you'll get a large wave. |
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DigiTan
Unregistered HyperCam 2
Super Elite (Last Title)
Joined: 10 Nov 2003
Posts: 4468
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| Posted: 04 Mar 2004 06:51:11 pm Post subject: |
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Quote: It is due to the inaccuracy of the graphing at large window settings. every pixel covers a couple of waves, so it doesn't get calculated exact enough to represent the real waves. try setting Xmax to 1440 and Xres to 2, you will get a similar effect, but when you change Xres to 1, it will be different.
So I guess you could say it's a screen resolution problem? |
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X1011
10100111001
Active Member
Joined: 14 Nov 2003
Posts: 657
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| Posted: 04 Mar 2004 08:07:03 pm Post subject: |
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| More like graphing resolution, if you could set Xres to something like .2, it would graph it correctly. |
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tyskis
Member
Joined: 20 Nov 2003
Posts: 238
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| Posted: 05 Mar 2004 02:07:19 am Post subject: |
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Just toying around  |
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