David Goodmanson

Last seen: 1 day ago | Active since 2012

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How to find the best fit curve as a vertical scaling of another curve?
Hi SojM, Suppose you have points x,y for the function f(x), where x and y are column vectors. And suppose the red points are t...

4 days ago | 0

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Answered
Solving a system of 4 equations to find the cosine directions from stress matrix and principle stress
Hi Trevor, After taking the terms involving sigma over to the right hand side, the equations are just the eigenvalue equation w...

5 days ago | 0

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Collatz Conjecture using for loop
Hello B, with disp = (N) you are creating a variable called 'disp'. You just need to change that command to: disp(N), Howeve...

7 days ago | 1

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How can i use the ifft() function properly?
Hi Andres, Shifting a function in time by t0 produces a factor of exp(2 pi i f t0) in the frequency domain. In this case it's ...

13 days ago | 1

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Answered
inverse Fourier transform without error problem
Hi MO, It turns out that the variable m is positive in most of its range, but is negative for the array elements >> [min(find(...

18 days ago | 1

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why the number of point of sfft and istft is different、
Hi neal, The documentation for stft says that if you want the number of sample points to be unaffected, then if the length of t...

19 days ago | 1

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How to solve hyperbolic equation with ratio?
Hi L^2, It never hurts to make a plot. Assume for the moment that z >1. Calling the right hand side of the equation f(x), the...

23 days ago | 0

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Request for help computing convolution of random variables via fft
Hi Jeff, It's nice to see a contribution of mine from almost four years ago come up, as just one of many people who have made c...

28 days ago | 1

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How to do multiple functions or subroutines in one .m file
Hi Collin Here is a quick example. Functions must go at the very end of the script, and each function must have an 'end' state...

30 days ago | 1

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spline interpolation of angular data
Hi mukesh, The regular cubic spline is using angle as the independent variable to define x and y parametrically in the usual wa...

30 days ago | 0

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Change the hot colormap so that the default value of 1 is white
Hi Matthew, The 'hot' colormap has white at one end of its scale and almost-black at the other. Suppose you successfully chang...

1 month ago | 0

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finding Annihilator matrix on the left for a matrix
HI Waqar, The matlab function null(A) creates a matrix such that A*null(A) = 0. But you want the matrix F to multiply A on the...

1 month ago | 1

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CDF of VOn Mises distribution
HI Aep, This is straight numerical integration and provides the cdf at 1e6 equally spaced points in theta, from -pi to pi. k...

1 month ago | 0

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How can I calculate in MATLAB-the electric field due to a time varying magentic field for a simple geometry?
Hello MC, From the plot it is not that easy to see what is going on since the two field colors are similar. Could you post a s...

1 month ago | 0

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How to make a colorbar with single color with varying intensity?
Hi Subhodh, I agree with Bjorn that it's possible to get caught up in this, and it is going to take some work to make something...

2 months ago | 0

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Computation of the bandwidth of a spectrum in wavelength domain
Hi Ikechi, the problem is basically that there are not enouch points to work with. lambda = lambdaaxis; lambda_range = (lambd...

2 months ago | 0

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Answered
How to calculate permutation powers
Hi lilly, Since the 1:n in the first row is just along for the ride, you don't have to carry it along in the calculation; you c...

2 months ago | 0

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Does pwelch function adopt already the correction factor due to the window?
hello sy, At this point I believe that the documentation is misleading in that it appears to imply Power/unit_frequency but the...

2 months ago | 1

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Answered
How do I define this integral function?
Hello LT, fun1 = @(x) x.^2 q1 = @(x) integral(fun1,0,4) q2 = integral(fun1,0,4) q1 = function_handle with value: ...

2 months ago | 0

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Answered
I am trying to solve for w using determinants
Hi Khaled, complex results do not seem right in this situation. M-M' ans = 0 0 0 0 % symmetric ...

2 months ago | 0

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Help on trigonometric equation solution. Thanks a lot!
Hi Jack, Fortunately the solver is coming up with the correct angle, except for the 2*pi ambiguity. So, after the solver does ...

2 months ago | 0

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Answered
Calculation the integral of the exponential of a matrix
Hi raha, I think you can go with the following technique, which does integration, differentiation etc. at the eigenvalue level....

2 months ago | 0

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Answered
Problem understanding PCA and eigenvectors of covariance matrix
Hello Jaime, Scores are not the eigenvalues of the covariance matrix. Rather, 'latent' have that role. Scores are projections...

2 months ago | 0

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Answered
Lotka-Volterra, can you estimate steady-state values from just exploring a plot?
Hi Kamila, Here is one fairly simple way to find the parameters. The two equations are dhare/dt = k1*hare - k2*hare*lynx dl...

2 months ago | 0

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How to solve a complicated equation?
Hi Cola, Since there is one equation and two unknowns, it must be possible to define, say, beta in terms of alpha, where alpha ...

2 months ago | 0

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What is the difference between unwrap() function and principal value in finding the unwrapped phase?
Hi Ansam, The atan2 function does not unwrap anything. It merely produces a four-quadrant theta, with -pi < theta <= pi. Co...

3 months ago | 1

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Answered
Fast Fourier Transform Issue
Hi Anas, suppose you have N = 1000 points over an interval of one second. The time array is t = (0:999)/1000. [see note below]...

3 months ago | 0

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Answered
LOG PEARSON TYPE III distribution
Hi Raj, MODIFIED Since the pearson type iii is a gamma distribution with a shifted and scaled variable, that means you can use...

3 months ago | 0

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real data FFT and reconstruction - frequency base issues
Hi Vmat. I believe that with 'rec' you may be confusing the time and frequency domains. The code below uses rec for the time d...

3 months ago | 0

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How to Solve sytem of 7 equations with 6 unknown variables? How to combine any two equations? equations and variables given belowRequest for help
Hello Vijaya, This is an overdetermined set of linear equations of the form M*x = b and can be solved in the least squares sens...

3 months ago | 0

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David Goodmanson