*PLOT FIELD VECTOR*

(sin(4*x+8*y),cos(4*x+8*y),0)

[Image Analyst]

Yeah, so? How about you explain something in English rather than just display a bunch of code? If there's a problem with quiver or inline, have you tried to figure it out by looking up the arguments and examples in the help? If you got an error, why didn't you post the error???

[justin Taylor]

http://i1203.photobucket.com/albums/bb396/kidstar079/Capture-2.png

[Walter Roberson]

I misread the original code; sub2ind() was not an appropriate solution.

What error message did you get originally? The sizes look okay to me when I work them through mentally.

[Naz]

I used the code you posted and did not get any errors

[justin Taylor]

Version Matlab Naz Use ?

[Walter Roberson]

It would save time if you were to post the error message that *you* encountered, or at least describe what the difference was between the output you got and the output you expected?

[justin Taylor]

sorry to bother you, I see you are very enthusiastic and I like that in your, i want find area surface limit x,y,z.

[Walter Roberson]

You want to find the surface area of a quiver plot??

What exactly are you asking us in this question? Are you encountering an error in the code you posted?

If you were asking us about how to find the area surface limit x,y,z then your code would have to have z in it somewhere. The closest you show is your F, which is only 2D, and "surface area" is not a phrase that is applied to a 2D object (the 2D term is just "area")

Do not just post code and expect us to know what you want to do!

[justin Taylor]

sorry ! because ihave got the wrong problem and i come from Viet Nam so my English not good! I hope you sympathize. I fix it.

[Walter Roberson]

Okay, so you have defined an x, y, and z, and you have indicated that you need to use quiver(). You have not, though, indicated what is to be done. quiver() requires an x and y (but not a z), and it requires two vector fields, u and v. You do not have enough variables defined, not unless you want to use quiver(x,y) with the x and the y acting as u and v matrices.

http://www.mathworks.com/help/techdoc/ref/quiver.html

Are you certain that you want to write the value sin(4*x+8*y) over top of x? And then to use the new x in calculating cos(4*x+8*y) that you then write over the old y ?

[justin Taylor]

Okay! i fix it.

[Walter Roberson]

I see you have edited your code, but you have not yet indicated what is to be done. What is the relationship between the F matrix and the quivers to be drawn? For the quiver() call you need an "x", a "y", a "u" and a "v" parameter: do the "x" and "y" parameters you wish to use correspond to your "x" and "y" variables?

[justin Taylor]

don't have u or v.

[Naz]

Can you edit your question and provide all information that is given to you as well as requirements?

[justin Taylor]

OK !

[Walter Roberson]

You removed all the useful information from your question...

Answer 1

[Walter Roberson]

>> t = linspace(0,4*pi,100);
>> [x,y] = ndgrid(t,t);
>> u = sin(4*x+8*y);
>> v = cos(4*x+8*y);
>> quiver(x,y,u,v)

[justin Taylor]

hi ! thanks very much !I have a week busy should not be able to regularly. I am very happy to be a stranger like you for help! We may be you are not?. Ah! you have facebook or yahoo chat?. I want to add friends with you ? My email on facebook is [e-mail].

[Walter Roberson]

I spend so much time working that I reserve my facebook account for communication that has nothing to do with work, such as chatting with my large number of cousins.

[justin Taylor]

So we could be good friends!

[justin Taylor]

Merry chistmat !