David Goodmanson

Last seen: Today | Active since 2012

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Answered
How to prove the positivity if this function?
Hi Andrea, What might constitute a proof using Matlab is a good question. If the answer to isAlways(y>=0) had come out as 1, w...

3 days ago | 0

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fixing of random number
Hi Irani, If I understand your question correctly, rng(1) Y = randi(10) rng('shuffle') node = randi(20) gives the same val...

3 days ago | 0

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how to find the angle subtended from origin to the poles in complex plane?
Hello Muhammed, it's as easy as angle(65+65j) angle(65-65j) with each angle in radians subtended from the x axis, -pi < angl...

9 days ago | 0

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Matlab and Fortran Precision Issue
Hello SA It's the constants. First of all for simplicity I commented out everythng not concerned with calculation of ORIGINAL_...

11 days ago | 0

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How do you inverse fourier transform 2D data only in one direction?
Hi Gabrielle, I'm not exactly sure what is meant by 'in the x direction' but it sounds like dimension 2. Anyway, ifft(Y,[],2)...

15 days ago | 0

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Principal Component Analysis: difference between V matrix from SVD decomposition and coef from pca?
Hello Jessica, The set of column vectors that define V in svd, or define coeff in pca, can differ from each other by a factor o...

17 days ago | 0

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extract roll pitch yaw rotation angles from 3D transform
Hello "AT" fwiw, here is a version of finding three rotation angles th1,th2,th3 from a 3d rotation matrix defined below. Ang...

17 days ago | 0

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my question is what is wrong with my code, the results should be in the first picture not the second.
Hi jana, the problem is that the if statements if mod(row,2)==0 && mod(col,2) ==1 && col>=3 % (b) and i...

26 days ago | 0

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My solver is giving extremely large numbers for a straight forward system of linear equations, what's wrong?
Hi John, What the solver is trying to tell you is that a solution does not exist for this problem, or more correctly it exists ...

26 days ago | 1

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Finding Argument of Bessel Function (1st Kind) to Return Known Solution
Hello 1:5, syms r ex = 5; R = 160; F = besselj(0,(2.405*r)/(R + ex)); Ratio = 0.3005; q = F == Ratio; vpasolve(q,r,[0 ...

30 days ago | 0

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Answered
Multiplication of sparse matrix and a normal matrix
Hi Amit, sum(S)' where the result is still sparse, or full(sum(S)') if you want a regular vector at that point.

1 month ago | 0

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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...

1 month 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...

1 month ago | 0

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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 ...

1 month 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(...

2 months 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 length of the ...

2 months ago | 1

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Answered
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...

2 months 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...

2 months ago | 1

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Answered
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...

2 months 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...

2 months 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...

2 months 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...

2 months ago | 1

Answered
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...

2 months 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...

2 months 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...

3 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...

3 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...

3 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...

3 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: ...

3 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 ...

3 months ago | 0