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I have a sine wave whose frequency is changing in irergular intervals from 50HZ to 55HZ and back to 50HZ.i need to extract the frequency information from the sin wave I need to plot the frequency vs time in a graph..
In this simple example, you can use the short-time Fourier transform to do this. You're really after something called the instan...

14 years ago | 0

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Answered
Small variation in amplitude
Just multiply the signal by a constant between 0 and 1 t = linspace(0,1,1000); x = cos(2*pi*100*t)+sin(2*pi*100*(t...

14 years ago | 0

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function acts differently in command window to when its run in a .m file.
What is getFileName returning? We need to know what that looks like For example, if you run it from the command line >>f...

14 years ago | 0

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Continuous Time Fourier Transform of a signal matrix
You stated in your original post that your matrix had an even number of elements, 100x2. In fact your matrix is 9079x2. You data...

14 years ago | 1

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Newbie: How to create a low pass that can be exported into c++?
Which MathWorks' products do you have? If you have MATLAB Coder, the Signal Processing Toolbox, and the DSP System Toolbox, you ...

14 years ago | 0

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Continuous Time Fourier Transform of a signal matrix
If the first column of your matrix is just the time vector with increments of 0.02 seconds, then just take the Fourier transform...

14 years ago | 0

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Answered
matlab error! "must return a column vector."
You don't help us to help you when you post a function that will not run like the one you have posted: function n_loss = F...

14 years ago | 0

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reading text file to matlab
Are the file names such that there is 1 per line in the text file? If so, the following works for me. I've just changed your ...

14 years ago | 0

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Answered
Is this a legal Matlab reseller?
I think you should contact MathWorks to determine which companies are authorized to sell MathWorks' products.

14 years ago | 0

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Size of Images varying
The Image Processing Toolbox has medfilt2

14 years ago | 0

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Autoregressive model using Yule-Walker method
You have to specify the order. One thing you can do is to specify a high order and return the reflection coefficients. The negat...

14 years ago | 0

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2D Matlab Plot help please
The x and y variables must have the same length. What relationship is there between xdata and Revs?

14 years ago | 0

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finding average of a percentile of rows in a matrix?
Assume A is your matrix. numrows = round(0.2*size(A,1)); lastrowstart = size(A,1)-numrows+1; lowermean = mean(A(1:num...

14 years ago | 0

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error using unique function
Is it a cell array of numeric values? You can use cell2mat() A = {1 5 9 ; 2 3 4; 2 4 5}; B = unique(cell2mat(A(:,1)))...

14 years ago | 1

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Minute error in array causes == to be ineffective
Hi Elliot, this is a reality of dealing with floating point numbers. You could use a tolerance a = randn(10,1); for ii =...

14 years ago | 0

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KB1 = conv2(b,Ksigma,'same')
When you convolve two matrices (images) of different sizes you get an output image that has row dimension equal to the sum of th...

14 years ago | 0

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How to interpolate a value between two values in an array?
Have you tried interp1? For example: t = 0:10; x = sin(t); tnew = 0:.25:10; xnew = interp1(t,x,tnew); plo...

14 years ago | 0

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how to do digital filter on this EEG data
I think Honglei has given you good advice. And I do think you should consider downsampling your data with decimate.m, or resampl...

14 years ago | 0

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How can I use the function 'affyread' in standalone applications?
Hi Prasanth, the function affyread is not supported by the compiler. You can see that here: <http://www.mathworks.com/product...

14 years ago | 1

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got an error "index exceed matrix dimension"
I think you should determine where the error is occurring. In other words, if you remove this for loop: for i=1:530 ...

14 years ago | 0

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changing the string "JF 2009" to two seperate strings "J 2009" " F2009"
One way: Amodified = A; B = char(A(:,3)); B(:,2) = []; B = cellstr(B); Amodified(:,3) = B;

14 years ago | 0

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MY QUESTION IS I WANT TO FIND THE MAXIMUM NO. FROM GIVEN DATA SET USING MATLAB CODE.
x = randn(1000,1); [maxval,I] = max(x); maxval gives the maximum value and I gives which element of the vector that maxi...

14 years ago | 0

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convolution of 2 sequestions
That depends on the structure of your text file. If it is a simple .txt file of numbers, you can just use load(), or dlmread(). ...

14 years ago | 0

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Defining a for loop
It depends on the range of your t variable and how finely you want to represent that. If 0<=t<=1, then you can't represent it...

14 years ago | 0

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Anyone can teach me about SSIM.m?
Have you read the paper and worked through the demos on the authors' website? <http://www.ece.uwaterloo.ca/~z70wang/research/...

14 years ago | 0

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visualize trend of temperature and rainfall data in matlab
If you want to use the scaling coefficients from a wavelet decomposition, then use wavedec() followed by wrcoef() with the 'a' o...

14 years ago | 0

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How accrues the delay in mfilt.firsrc ?
Hi Stef, you can find that by hm = mfilt.firsrc(l,m); mean(grpdelay(hm))/m % now start the output signal at 12+1 y...

14 years ago | 0

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Answered
Is there a function in matlab that finds a transmition function of a filter, based on the input and output signals?
You can use tfestimate() in the Signal Processing Toolbox to estimate the transfer function. In the System Identification Too...

14 years ago | 0

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My signal level is strange.
It looks like you are just implementing this difference equation A = [1 -2 1]; B = [1 0 0 0 0 -2 0 0 0 0 0 1]; y = fil...

14 years ago | 0

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Create a 4-pole, 300-6000HZ bandpass butterworth filter?
If you want 4 poles and you have a bandpass filter, then you have to specify the order as 2. Also to convert from normalized fre...

14 years ago | 0

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