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2D data fit lsqcurvefit with NaN in grid
You could try doing this with lsqnonlin: x = [1 2 4 6 8 10 13 17 21 25]; y = [0.2 0.5 1 2 4 7 10 14 18 22]; z =[1,0.6844,0.30...

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Calculation of consistent initial conditions for ODE
@Fabio Freschi, OK, now we're at least in the same general region of worrying. If I read decic correctly the use of the QR-outpu...

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How to plot 3D suraface and contour lines?
To effectively use matlab sometimes one has to make functions vectorized - such that you can feed the function arrays and get al...

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help code with lsqnonlin
At the very least you'll have to make Nest into a function - otherwise you have nothing to optimize. Perhaps something like this...

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Could you please help me generate following function and solve the integral?
To calculate the area under a curve specified by numerical arrays (x and y) you can use trapz: A = trapz(x,y); % Or in your c...

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Custom fitting using equation from differential function
Use matlabFunction to make a function out of the symbolic solution, then fit that one numerically to your data: R_a_fcn = matla...

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Double parameter optimisation using optimisation toolbox
The standard fitting method I use is: % Your curve-function definition (I just mock one up, if you have it defined in a % mat...

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legend for multiple plots
Use the outputs from plot to explicitly control what is show in the legend: x=1:15 ph1 = plot(x,res540,'-r'); hold on ph2 = ...

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The contour function requires Z=f(x,y); I have measured data for X,Y, and Z that are not related with a function. I get errors when I use Z as a X:1 array
You will have to look at the scatteredInterpolant or TriScatteredInterp and possibly also its related griddata functions, check ...

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ismember(a, b) function problem
The ismember function checks if elements in a are found in b, not that each element match. In your case both "1" in a have a val...

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Generate nchoosek vectors line-by-line
There are loads of nchoosek functions available on the file exchange: nchoosek. Some of those should help you with this. I recal...

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Parameter Estimates for Ordinary Differential Equation
Solve the ODE analytically. That will give you an expression for T(t,c1) this you can then use for a standart non-linear least-s...

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3D Polar Plot
A quick search on the file exchange leads to these submissions:pcolor-in-polar-coordinates, 3d-polar-plot and polar-contour-plot...

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Struggling trying to create a 2-D contour plot from a large data set from x and y coordinates and corresponding frequency value
Wouldn't something like this do: % Mock-up of data similar to yours... x = linspace(-5,5,501); y0 = linspace(-2,2,201); [x,y...

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Add legend for a specific plot
Explicitly use the handles returned from the plotting-functions: legend([l1(:);l2(:);l3(:)],'text1_1','text1_2','and','so','on'...

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Solve differential equation from Matlab
For a numerical integration of this ODE look at the help and documentation for ode45 and its siblings, also look at the examples...

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How to smoothen contourf plot to make it look better
Best way (probably) to go about making your contourlines smoother is to interpolate your data: Xi = linspace(min(X(:)),max(X(:)...

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variable number of if condition
Maybe something like this: for i = min:max %:columns b = 1; d = 1; f = 1; for a = 1:length(Ex) for i_c...

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Why does this code generate a mix of integers and doubles?
In practice you can look on this problem as "good luck" and "bad luck" when it comes to working and not working. The rounding of...

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Remove noise from the image
First start by trying standard filtering-methods. Compare what you get with 2-D median-filter (medfilt2), and Lee's sigma-filter...

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Function GUNZIP was unable to read URL ''http://opihi.cs.uvic.ca/sound/genres.tar.gz''.
If the file doesn't exist then nothing will be able to read it. I wouldn't bother using gunzip, I'd go for straight downloading ...

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True north-based azimuths
Your question doesn't make much sense, sure you can do that - but that would be more of "establishing" your azimuth-convention. ...

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Incorrect dimensions for raising a matrix to a power
Just set a debug-stop in that function and check what dimensions your variables have: dbstop in gaussh Or just at the point wh...

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Filtering the large precipitation data for finding rainfall events
If you store your rain-fall-data in an array, r_f for rain_falls, with n_t rows and n_stations columns you could easily do thing...

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How to fit regression
This is not a polynomial, therefore you cannot use polyfit. You can seamlessly use any least-square fitting routine to fit your ...

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curve of best fit
In order to get a function that has two y-values for for some range of x-values you will cannot fit a polynomial such that y=p(x...

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how can compute a marginal distribution?
Look at the help and documentation for the histogram-function. Possibly also check the histogram2. HTH

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Solving a system of linear equations with lots of o coefficients.
Matlab is designed to solve systems of linear equations. It is one of the fundamental operators of its matrix-algebra: % Your p...

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Reading and analysing files in subfolders - indexing
Why not skip the generation of FileName and index into files directly inside the loop: dt = 0.005; tt = 0:dt:60; files = dir(...

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Trajectorys of 4 objects on 3D plane not symmetrical
Your main problem (or rather: step to take) is that you do the calculations element-by-element in the different arrays. That is ...

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