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ZeluX
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Joined: 19 Oct 2004
Posts: 6
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 Posted: 27 Oct 2004 03:00:11 pm Post subject: |
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| Is there a way to find out the angle between 2 graphs? |
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Arcane Wizard
`semi-hippie`
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Posts: 8993
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| Posted: 27 Oct 2004 03:08:57 pm Post subject: |
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you mean like this?
f(x) = 2x²-2 and g(x) = 4x²-2x+2
f'(x) = 4x
g'(x) = 8x-2
f'(1) = 4
g'(1) = 6
tan-1(4/1 = 75.96
tan-1(6/1 = 80.54
80.54 - 75.96 = 4.57 degrees
Last edited by Guest on 27 Oct 2004 03:09:29 pm; edited 1 time in total |
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DarkerLine
ceci n'est pas une |
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Joined: 04 Nov 2003
Posts: 8328
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| Posted: 27 Oct 2004 03:50:59 pm Post subject: |
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f'(x) is the derivative at x. You can compute it on the TI-83+ in 2 ways:
1 - graph the function. Press [2nd][calc] and select 6:dy/dx.
2 - the nDeriv function. To find the derivative of f(x) do nDeriv(f(x), x, point. Example: nDeriv(X^2,X,5 calculates the derivative of X^2 at 5 with respect to X.
on the TI-89 this is even easier. d(f(x),x) returns the derivative of f(x) as a function of x, you can then substitute the value of x. |
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Arcane Wizard
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| Posted: 27 Oct 2004 04:10:06 pm Post subject: |
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| It's easier doing it without a calc, though. |
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DarkerLine
ceci n'est pas une |
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Joined: 04 Nov 2003
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| Posted: 27 Oct 2004 04:13:15 pm Post subject: |
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| For people who know how to do it, yeah. |
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Brazucs
I have no idea what my avatar is.
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Joined: 31 Mar 2004
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| Posted: 27 Oct 2004 06:49:08 pm Post subject: |
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| It can get tough with Power Rule and Division and Chain Rule and crap. That's why I got an 89, the AP exam is timed. |
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DarkerLine
ceci n'est pas une |
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| Posted: 27 Oct 2004 07:34:17 pm Post subject: |
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brazucs16 wrote: It can get tough with Power Rule and Division and Chain Rule and crap. That's why I got an 89, the AP exam is timed.
Puh-leeze. I can't remember a single time I needed a calculator for that thing. Except, yeah, when we had a contest to see who could get the highest score in ZTetris before the exam ended... |
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DigiTan
Unregistered HyperCam 2
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Joined: 10 Nov 2003
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| Posted: 27 Oct 2004 09:33:15 pm Post subject: |
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| Well, things can get pretty hairy if mixed terms are involved. I can't remember what they call this, but "e^x * sin(x)" is a good example. Solveable by hand? Absolutely. But the calc would be my first choice. Anyway, I would (talking to ZeluX, now) practice the Arcane way before turning to a calculator. It's the only way to really learn the material. |
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Arcane Wizard
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Posts: 8993
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| Posted: 28 Oct 2004 01:37:43 am Post subject: |
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| Don't you need to put like "= value" next to it in order to be able to solve it? |
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ZeluX
Newbie
Joined: 19 Oct 2004
Posts: 6
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| Posted: 28 Oct 2004 09:35:39 am Post subject: |
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| Thanx for all your help. I know how to derivate "for hand" but wanted to know howto for a science prog. I'm planning on doing to increase my understanding of basic. |
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DigiTan
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| Posted: 28 Oct 2004 01:49:11 pm Post subject: |
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That's a good strategy. I don't know how to do it in a prog, but you can find the slope at any point using "dy/dx" in the CALC menu. Then just substitute those values into TAN-1(x) to get the angle. I'm no BASIC expert, maybe the other guys here can confirm this for me.
[quote name='"Arcane Wizard @ Oct 28 2004' date=' 01:37"']Don't you need to put like "= value" next to it in order to be able to solve it?[/quote]
I remember now, they call it the "product/quotient rule." They're very bothersome. |
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Arcane Wizard
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| Posted: 28 Oct 2004 02:11:29 pm Post subject: |
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DigiTan wrote: That's a good strategy. I don't know how to do it in a prog, but you can find the slope at any point using "dy/dx" in the CALC menu. Then just substitute those values into TAN-1(x) to get the angle. I'm no BASIC expert, maybe the other guys here can confirm this for me.
Try reading the second and third post in this topic. |
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DigiTan
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| Posted: 28 Oct 2004 02:43:25 pm Post subject: |
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| Oops. Forgot Sir Robin already meanted that. |
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Brazucs
I have no idea what my avatar is.
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Joined: 31 Mar 2004
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| Posted: 30 Oct 2004 03:48:30 pm Post subject: |
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| some guy made an 83 program that can do derivatives the way the 89 does it, just not as well. He cheated, though: used instrings. |
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DigiTan
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| Posted: 30 Oct 2004 06:54:54 pm Post subject: |
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| Do you mean like Pretty Print for the 68k machines? (I guess this is what ZeluX might've had in mind). That's really tough to pull of in BASIC, even if it were very incomplete. |
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DarkerLine
ceci n'est pas une |
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| Posted: 30 Oct 2004 08:25:08 pm Post subject: |
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brazucs16 wrote: some guy made an 83 program that can do derivatives the way the 89 does it, just not as well. He cheated, though: used instrings.
how's that cheating though?
I wrote a Basic differentiation program for the 83+ once. It used a subprogram similar to the "part(" function for the TI-89, and did everything else almost the same as the example differentiation program in the TI-89 manual. It wasn't good at simplifying though, I had to write some of that myself as well.. |
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Math and Science => Technology & Calculator Open Topic
