Survey posted 2003-06-06 23:32 by Henrik.

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Umm... i think this is a 3d 'SINC' GRAPH.

If so the graph that uses the WHEN fuction IS EXACTLY correct. This is what the MATLAB 6 Manual has to say about the SINC function

sinc(x)=sin(x)/x

To display in color type this:
[X,Y] = meshgrid(-8:.5:8);
R = sqrt(X.^2 + Y.^2) + eps;
% (the eps just prevents sin(0)/0 by adding
% the smallest number your system can handle
Z = sin(R)./R;
mesh(X,Y,Z,'EdgeColor','black')
surf(X,Y,Z)
colormap hsv
colorbar
-------------------------
I tested this, and it looks almost identical to the graph in question. The window size may have to be adjusted slightly though. (i have no clue how to do that)

I hope this helps.

Now what is that graph that is shown on the case of the ti-89? (I know it is actually construced with 2 graphs and shading.)

Hmm...
I wonder how many of the people who answered yes actually CAN reproduce the graph. I can't. Don't know how. Don't care how.

For those who have said yes I haven't seen an equation that works. But of course I have to try them all first...

Check the first set of equations.

z = sinc (|x+y|), should be correct. How your window is set and how TI want it I shall never know.
where |x+y| is the modulus / magnitude of two independent ...directions, so don't just add x & y

what does the graph z = sin(|x+y|) look like? That could be rather funky.

(What is the correct word for a non-scalar value?, I can't for the life of me remember it.)
And what is the word for people who keep forgeting normal words completely randomly. I have looked it up before and can never remember it - I am not joking.

You would write sinc(|x+y|) like sin(|x+y|)/(|x+y|) right?

I don't know :(... sinc is stupid. Since we're going to be typing the equation in on the calculator, type it on here they way we'd type it on there.

Instead of sinc(x), use sin(x)/x

It scares me! *hides*

But I won't be typing it in on a calculator - or are you going to send me a fancy new calc. My 82 doesn't do 3D.
So sinc is a perfectly fine way of writing it.

and to confirm the original question.
sinc(stuff in brackets) =
sine(stuff in brackets) / stuff in brackets

with sine being the not so lasy way of spelling sin. (I don't won't people thinking I am being naughty now do I)

Sin... LOL, I always thought that was funny :)

Are you saying that it would be possible to make that graph on the TI-82? *gets TI-82 out*

Not without writing your own app to do it.
You can do the 2D version though.

Hey, do you think DS would ever port Graph^3 to the TI-82 as an ASM program?

I didn't think so either. ;-)

Is it true that you can just download the AMS and plug that into VTI. If so, I think I might do that to play around with this 3D graphing thing. I only 83+, you see, and it's too full of games to put a flash app like Graph3 on there.

OMG, back up your games and then delete them to make room for Graph³. Then put them back later...

All this stuff is way too heavy for me. I thought that I was in high-level math, but I have never seen some of this stuff. I have never graphed 3D, and I have never been over trig -- though not that it is not in the curriculum, it is just that my teachers never got to the stuff, and I don't have the work ethic to teach myself. I feel incredibly inferior to just about everyone right -- except the guy who didn't know what "e" was. I guess I am not at the bottom just yet, but I am pretty close.

-W-

Good luck :)... if that helps

LOL, I'm just in Hon Alg 2, but I try to take every chance that I can to learn something new in math, whenever I can...

I just took and enrichment test, and I ran into f'(x)=... Is that the same thing is a derivate? (I'm thinking of d/dx[...]) If it is, I need to kill myself because I could have answered three or so more questions.

This is a perfect chance for me to be smart!

f(x), is said as "f of x". It is what is known as a function. Sound familiar? It should because lines are functions. f(x) can be used instead of "y". Also, it can be like f(2)=2x+3. Which means f(x)=7. It is just that simple.

-Not wanting to go into inverse functions, I am W-

He was asking for "f prime of x," not "f of x."
And furthermore,
"Also, it can be like f(2)=2x+3. Which means f(x)=7."
This sentence does not make sense.

He means to substitute the 2 in for x...
f(x)=2x+3
f(2)=7

... I know... I've known that for a LONG time...

There was an apostraphe after the f... f'(x) Maybe the ASCII is making it not show up...

f ' (x)

Yes.
f'(x) is Newton's notation.
dy/dx or d/dx f(x) is the Leibniz notation.
The pros about Leibniz notation include telling us what variable we are differentiating with respect to.
The pros about Newton's notation include giving us a place to write the number where x should be evaluated at, for example f'(3); with Leibniz, you got to right a big slash or verticle bar, which takes more time.
I personally use both of them depending on what I am trying to achieve.

Damn... then I knew how to answer the question. I learned a little bit about derivatives from using the TI-89 and just playing around with it. It uses the Leibnez notation, then, I guess. Can it use Newton's also?
I feel sort of stupid now, but at least I understand what they meant now... Thanks! :)

Realising that you don't know everything means that you know more than most people.

Knowing that you really know nothing in the great scheme of things means that you know all you need to know to get on in life.


So don't feel stupid - you are NOT.
"Small bits of knowledge can be picked up 10 a penny, but understanding and solving the problem is something that truely shows intelligence".

And, unfortunately too few people can do that now - they just regurgitate facts.