MATLAB Central Newsreader Recent Posts

create grayscale star sign

Julia Woody — Sat, 04 Jul 2009 09:39:01 -0400

Hi all,

I have a 256x256 sized image as;

image=zeros(256,256)

and I want to create a grayscale colored star sign on this image. How to do this? what is the code for this?

NI-daq on a mac?

kees de Kapper — Sat, 04 Jul 2009 08:54:01 -0400

Dear all,

as stated somewhere here on the newsgroups, there is still no official support for the NI-DAQmx drivers in the Mac OSX version of Matlab.
However, I was wondering if somebody ever had made some "homebrewed" drivers to access the NI-daq's (USB). Or is there someone who knows how to access the ni-daq library to use the functions stated in the NIDAQmxBase.h file within the OSX environment?

Thanx in advance!

Kees

Give me a good example for accumarray()

Husam Aldahiyat — Sat, 04 Jul 2009 08:54:01 -0400

Hello,
I am learning MATLAB and when I read about the accumarray() function it looks good but I didn't understand how the examples worked.

Could someone give me a nice small example (problem) and how accumarray solves it?

profile matching

Anil N — Sat, 04 Jul 2009 08:42:01 -0400

Can any one know profile creating and matching in an image?

centerline delineation

Anil N — Sat, 04 Jul 2009 08:40:02 -0400

Hi,

I am working on road extraction using satellite images, I have extracted the road boundaries using some method, by using that i want to delineate the center line, can any one help me how to do this?

with thanks
anil

Need Help in GUI/Figure File

Fake Ghost — Sat, 04 Jul 2009 08:39:01 -0400

Hi everybudy:
i need help with gui/figure File please help.
i want to do is to show dynamic pictures in fig file.
but those dynamic picture are produced by another function which is not part of that figure file.

recognition module is producing two pictures dynamically and i want to show them on the figure file. please help.

here is the layout what i want to do.

On top of the figure file i want my detection webcam view and at bottom i want recognition picture, one test image and other the recognized image. please tell me how i can do that. if i m not that clear then please reply and give me ur email i will send u the screen shoot of what i want to do. please help.

thanks in advance

Aligning of different images

Nirmal — Sat, 04 Jul 2009 08:37:01 -0400

How to align two different images having little information in common?

Thank you.

Matlab R2009a Installation Error?

Uzumaki — Sat, 04 Jul 2009 08:24:01 -0400

My OS is Windows Vista 32bit. When installing Matlab r2009a I got the following error:

There was an unexpected exception:
External process (C:\Windows\system32\regsvr32.exe /s "C:\Program Files\MATLAB\R2009a\bin\win32\LinkCCS.dll") did not return after 10000 milliseconds"

After that, the installer continued its work and succeeded, however I still wonder what was the above error? Could I just ignore it and use Matlab as though nothing has happened?

Thanks!

Uzumaki

Re: Plot an image and rotate it in 3d?

haidar master — Sat, 04 Jul 2009 07:58:01 -0400

Please, can you help me?

I want to plot any Image in 3-d like Lena.bmp... can you write to me the code in matlab for drow the image in 3-d?

with my best regards

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fft for beginners

JMMO MartinOlalla — Sat, 04 Jul 2009 06:44:02 -0400

Hi all,

I am just starting doing fft with MatLab. No previous experience.

I am working with 2^19 experimental data points extending over some 50hours arranged as a vector X whose length is 2^19. I am getting on the fft since I need to study correlations and convutions in sets of different experimental data (so ifft will be also needed)

Since the rate of time in the experimental data is known I can control easily what the index of X means: say, from X(1,i) to X(1,i+1) there are 0.11ms while, of course, the first datapoint is t=0.

Now, I got: W=fft(X), which is again a vector whose length is 2^19.

My question is how is the index of this vector W running in the frequency domain? Say, low index means low frequency? frequencies are equally spaced? on what basis?

Also, I would like to know what would I be doing if I fftshift the vector W.

Thanks in advance.

Photovoltaic cell array model

Peng Lei — Sat, 04 Jul 2009 04:59:02 -0400

Hi,
I'm doing research on Photovoltaic simulation and its control. I need to built a PV cell array model by Matlab / Simpower system which will meet all the I-V, P-V characteristics. Just got no idea how to build this model by Simpower. Any body can give me any clue?

I appreciate the assistant.

pde solution for simple problem

NURUL — Sat, 04 Jul 2009 04:47:01 -0400

Hi there<
Solving PDE using Matlab
## type 1
I have a pde of this type:
1/2/P*(1-r^2)del_c/del_x=del^2_c/del_r^2+1/r*del_c/del_r
Where P is a constant, r and x is radial and axial direction respectively (nondimensional), c is a non dimension function
The two boundary conditions are:
c=1, at x=0, for all positive r
c=0, at r=1 for all positive x
Finally I need:
for all del_c/del_r, at r=1
## type 2
The original equation is now:
1/2/P*(1-r^2)del_c/del_x=del^2_c/del_r^2+1/r*del_c/del_r+del^2_c/del_x^2
Everything else remains the same.

Please send the solution to docnurulhasan@gmail.com if you have one.

Re: RobustFit goodness of fit

Stephen — Sat, 04 Jul 2009 04:11:01 -0400

"Tom Lane" <tlane@mathworks.com> wrote in message <gi6899$mee$1@fred.mathworks.com>...
> > I'd like to know how to 'understand' the goodness of fit of a Robust
> > regression by the stats result (r,s,robust_s, etc)
>
> Cristiano, if you type "edit robustfit" and look below the regular help
> text, you will find some additional comments listing references. The paper
> by DuMouchel and O'Brien talks about this issue.
>
> -- Tom
>

The robust fitting and curvefit functions are incredibly useful, but...it would be nice if the help for the functions went a little farther in explaining what was being calculated. For example, it is not clear what r^2 means for robust fitting since it must be different from what is done for OLS and presumably incorporates the weighting used in the fit. Since you have coded some particular equations in the m-file, why not write them down? Also - it would be nice if robustfit.m included the r^2 that is given in curvefit.
Stephen
ps: unfortunately the DuMouchel and O'Brien paper seems to be the rare case of something not available online.