# David Goodmanson

### David Goodmanson

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Why do the limits of the following two equations have opposite signs? (MATLAB R2024a Update 1 _20240418)

Hello dq, I think the behaviour is reasonably clear. The first example is limit((1-(-1)^n)/n, n, 0) = -pi*i. If you look at ...

3 days ago | 0

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Issue in getting correct probabilities for Landau Zener Problem

Hello Aryaman, I believe your step sizes are too large, but the first issue is, in the for loop you define a=v*t(i)/2; but then...

12 days ago | 0

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periodic angular acceleration of mechabism

Hi Alberto, (modified once more) If you apply a constant torque tau and advance the angle of the crank by an angle u, then you...

17 days ago | 0

What does the period in line 20 ( after v)represent and why is it needed

Hi Bob, f is a vector with 1000 elements and consequently, so is the denominator. The dot allows matlab to divide each of the ...

20 days ago | 0

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Fixed-step size: why doesn't the Nyquist-Shannon sampling theorem work?

Hello Zahara, The Nyquist theorem gives you the bare minimum number of points to describe the oscillation. More points are bet...

25 days ago | 0

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caculate confidence interval from customized pdf

Hello SX, Ordinarily to find the cdfs you would have to use numerical integration. In this case for the normal distributions, ...

1 month ago | 1

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Helmholtz problem in circular disk

Hi Athanasios, the problem is with the table of zeros of the bessel functions. Counting starts with the first nonzero value, s...

1 month ago | 1

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How can it be that my continuous relative phase exceeds 360 degrees?

Hello Suuz, There is nothing inherently wrong with a phase angle of more than 360 degrees. In fact such a phase can be valuabl...

1 month ago | 0

Symbolic derivative in a sum

Hello OG, If you know d/dp G for the elements of G, you can use d/dp G^-1 = -G^-1 (d/dp G) G^-1 which is all right numericall...

1 month ago | 0

Solving complex linear equations with conjugate operations

Hello SB, Any way you look at it you have four independent unknown quantities, but there is some choice of their form. For the...

1 month ago | 0

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Confusing THD value for a Signal without Harmonics

Hi weinan, MODIFIED The thd process widens the peaks, as shown by the plot produced when you invoke thd. When the frequency i...

2 months ago | 1

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I'm trying to get code to show the increase of density from the center outward.

Hi Matthew, you could try a cutaway view (which doesn't represent the sphere as a solid) n = 40; r0 = 5; [x y z] = sphere(n...

2 months ago | 0

Plotting the profile of an airfoil generated by random NACA numbers.

Hello Keaton, I changed the line TT0 = string(:,3:4) to TT0 = string(:,3) since the program does not run otherwise. ...

2 months ago | 0

Antipodal and Unipolar Analytical Curve

Hello James, For the analytical part, you get an exact match for the curves by replacing Pb_antipodal_analytical = erfc(sqrt(2...

2 months ago | 0

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Total Least squares error help. I tried a couple different things here, but i'm not exactly sure how to do a total least squares error. The numbers aren't making sense to me.

Hi Rian, the problem is that b is a column vector, but predictionvalues is a row vector. Using predictionvalues = m([0, 1, 2,...

2 months ago | 1

pearsrnd and pearspdf are not coherent for the Pearson IV distribution?

Hello Marco, It appears that you are implicating the pearson rand function here, but I believe the real culprit is the pearson ...

2 months ago | 1

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Problem with damping constant affecting displacement in a mass system displacement system

Hi Daneil, I don't see any signs that your calculation is incorrect, although in some cases you may have to run the calculation...

2 months ago | 0

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Interpolation schemes that produce positive second derivatives of the interpolant

Hi SW, Here is one way to go about it. The data has 10 closely spaced points and one well separated point x(11). Fit the firs...

3 months ago | 0

3D Fourier Series fftn?

Hi sbr Absolutely this is a 3d fourier series. The reason that the normalization 1/8*LxLyLz does not depend on grid size is th...

3 months ago | 0

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Finding nice color bar limits automatically

Hi William, It looks like you want to move from the limits you have to some with fewer significant figures such as 1 or 2. Her...

3 months ago | 0

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What are the point locations for EHfields() function output?

Hi XC, I don't have the antenna toolbox but there are definite indications that they are using the sphere command. Sphere has ...

3 months ago | 0

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Antenna Element Calibration File Size Calculation

Hi John, assuming the required memory is the product of those four factors, then if these are 64 bit floating point real number...

3 months ago | 0

Reciprocity mismatch using geodetic2aer and aer2geodetic

Hi Leonardo, There is no reason for the reciprocity you mentioned to hold true. This has to be the case since the aer coodinat...

3 months ago | 0

Can I assign vectors with different number of rows per-column to a matrix?

Hi Abdallah, Cell arrays are very versatile but they are also on the slow side. Depending on what you are doing, that may not ...

3 months ago | 0

How do I solve this ODE system where there exists derivatives in both sides?

Hi Arda, These two equations are of the form p' Jxx - r' Jxz = f(...) where ... = p,q,r,J,J,M,M (a bunch of known stu...

4 months ago | 0

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How can I create randomly scattered points between two circles?

(At Adam's suggestion I moved my previous comment to this answer) What tells the tale is the differential area element in the (...

4 months ago | 3

Hi, everyone! I have a question about generating random meshgrid.

Hello yc, If you are willing to make an approximation to the area of each grid quadrilateral then I think there is a reasonably...

4 months ago | 0

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Voltage peaks after opening of a contactor in an inductive circuit

Hello Ivan, I'm not sure how you obtain 17.5kV from 500A and 50ns, and 50ns seems really fast if the contactor is mechanical, b...

4 months ago | 0

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How to perform a coordinate transformation in a function?

Hi Kovacs Here is one way. Clearly x^2 + t^2 = xi^2 by inspection, so that factor, which is common to both terms, can be sav...

4 months ago | 1

| accepted

How can I write "StruveL function" in matlab?

Hello Shreen, Here are two ways although you will need the symbolics toolbox for the first one. I used benign values for z and...

4 months ago | 0

| accepted