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David Goodmanson


Last seen: Today |  Active since 2012

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Answered
Write different super gaussian function with same fwhm but different order
Hi Hugo, There seems to be some confusion as to whether the constant that is used as the reference constant between various val...

11 days ago | 0

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Answered
Error in executing freqz command on LINUX server
Hi Neuling, If all else fails you could just write your own version. Something like function [H w] = freqz1(b,a,n); % parall...

25 days ago | 0

| accepted

Answered
problem using fplot for small arguments of spherical bessel functions
Hi Donaldo, As you probably know, the function works pretty well except for small values of r around the origin where you see a...

25 days ago | 1

Answered
SVPWM abnormal current under inductive load
Hi Bahdir, I believe the effect is real and can't be 'solved'. When the loads are purely resitive, the current and voltage are...

1 month ago | 0

Answered
Hello everyone, I have a question about numerical integration. The formula is shown below, where the integration path C_beta is a closed curve on the complex plane.
Hi MJ, The result depends on what goes on in the complex plane, so as an intro here are some plots of the angle of functions f(...

1 month ago | 0

Answered
How do I apply a gravitational gradient to this code? (particles in elastic collision)
Hi Alex If you don't need the details of the actual trajectory, the method is pretty simple. Modeling the asteroid as a sphere...

2 months ago | 0

Answered
How do I find the equation of points on a spline curve?
Hi Aiden, you have to remember that for each section of the spline, the polynomial is local to that section, i.e. the argument ...

2 months ago | 0

Answered
When I use ode45 to solve a state space equation, the solution will be diverge. Interestingly, if I set the ma (which I've overstriked) to zero, the result will be converge.
Hi Z^2, It's not easy to say for sure without seeing the actual model, but I think there is a decent chance that your C matrix ...

2 months ago | 0

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Answered
Finding the Analytical Equation q(t) for an RLC Circuit Using Given V(t) Data
Hi Trais, The exact solution for q(t) involves integrating the voltage for times less than t. Let w = sqrt(-R^2/4L^2 + 1/LC) ...

2 months ago | 0

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Answered
Inverse fft doesn't match analytical formulation
Hi SW, There is a sign error in your transform pair, which should be 1/w^2 <--> -|x|/2 not 1/w^2 <--> |x|/2 As has been n...

2 months ago | 1

Answered
why the voltage across a resistor with two different input DC source is the avg of the two different input DC voltage
Hi RAM, The 1 ohm resistor is quite a bit larger than the two .01 ohm resistors so in a first approximation the 1 ohm resistor ...

3 months ago | 0

Answered
INTEGARTION OF BESSELH function
Hi george, I don't know what the values of your parameters are, but it appears that the problem with Escat is that besselh(0,2...

3 months ago | 0

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Answered
No feasible solution found
Hi Preston, It seems likely that this is a planar structure with the diagonal elements having length sqrt(2). (If all th...

3 months ago | 0

Answered
2D Fourier transform- problems with the shift
Hi nathan, It is a bit more inconvenent but you can reconstruct using a shifted grid as you did. I kept that method in in the ...

4 months ago | 0

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Answered
How to find indices of resampled values from the indices of the original values?
Hello Mibang, Rather than snew = resample(s,fsnew,fs) I think it's safer to use [snew tnew] = resample(s,t,fsnew) because t...

4 months ago | 1

Answered
fft and ifft of signal seem to cause time reversal
Hi sgreess, I'm guessing your input signal is a column vector. In that case the command spectra = spectra' by Matlab conven...

4 months ago | 0

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Answered
How to fit this model with a Weibull distribution?
Hi MIchele, One possibility is that you are not fitting the correct statistical function to the data. The algebraic expression...

5 months ago | 0

Answered
Problem with integration: there is a pole on a contour
Hi SB You can use the principal value for the integration,which is defined as (1/2) * [ (integral with path on one side of the...

5 months ago | 1

| accepted

Answered
Generalised solution to a n-order system of equations
HI Aden, Here is a method that produces, within 4.5 %, the experimental value a_1 = 2.518. The equation is (for simplicty n-1 ...

5 months ago | 1

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Answered
Solve more complex problems in matlab
HI OF, y(x) = (m-2)x^2 -3mx + (m+2) The domain of m where the two roots have opposite sign is a numerical question and I think...

6 months ago | 0

Answered
How can I scale and plot the graph according to the formula I use?
Hi Zaref, One thing for sure about eq.(19) in the attachment is that eps0 can't be in the numerator. eps_m is dimensionless (a...

6 months ago | 0

Answered
Plotting Complex Functions.
Hello Sudharsana, Do you mean f(t) = exp(-ar/(twC))*exp(-ai/(twC)) or f(t) = exp(-ar/(twC))*exp(-i*ai/(twC)) ...

6 months ago | 0

Answered
How to apply orientation constraints between two rigid bodies
Hi Aiden, because of the parallelism there are only two degrees of freedom here (assuming that one pivot point is the hole nea...

6 months ago | 1

Answered
How to generate white noise signal from a given PSD?
One can just create the desired waveform that has psd = S0 without resorting to S/N. The example below has a crazy large unphys...

6 months ago | 0

Answered
How can I replace the upper off diagonal(super diagonal) and lower off diagonal(sub diagonal) of a matrix?
Hello Olawale m = rand(5,5) m1 = diag(m,1) % original upper diagonal a = [2 3 4 5]' % new upper diagonal elements mn...

6 months ago | 1

Answered
double and triple integral for a complex function. I coded but did not get any output
Hi Orpita, Here is a way to at least reduce the dimension of the integral from 5d to 3d. First of all, the quantity (x+1/2) se...

7 months ago | 0

Answered
Logarithmic trendline equation of data
Hello Cem, As has been mentioned you can use the curve fitting toolbox for this job, but if you don't have it you can try a sim...

7 months ago | 0

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Answered
How change two columns with 5 rows to a single row?
Hi Bajdar, xy = [x; y]; z = xy(:)' i.e. concatenate x and y vertically, read that matrix out columnwise, then take the transp...

7 months ago | 0

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Answered
Hi, I am applying findpeaks function to find the peaks of an oscilloscope signal but in the peak plot graph it is automatically changing the x-label with a large difference.
Hi Rikita, if you use findpeaks(y,x) where x is the x axis (linear or log scale) whose min and max match the oscilloscope trace ...

7 months ago | 0

Answered
Why such a fuss with ndgrid and meshgrid issues?
Hi Kristoffer, I totally agree that Mathworks should use nonsquare examples in the documentation for meshgrid, ndgrid, surf etc...

8 months ago | 1

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