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David Goodmanson


Last seen: Today |  Active since 2012

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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 ...

4 days 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 ...

5 days 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) ...

9 days ago | 0

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...

15 days 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 ...

28 days 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...

30 days 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...

1 month 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 ...

2 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...

2 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...

2 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...

3 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...

3 months ago | 1

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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 ...

3 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...

4 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...

4 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)) ...

4 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...

4 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...

4 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...

4 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...

5 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...

5 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...

5 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 ...

5 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...

6 months ago | 1

Answered
How do I find the phase for a periodic cos wave using fft?
Hi Noam, here is a version using time and frequency in the usual manner. A couple of ponts here. If you construct a grid as y...

6 months ago | 0

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Answered
how to write the right code to measure the elapsed time of this method d1 = diag(1./diag(A))
Hi Amna, A common way to do this is with tic and toc. So: a = rand(1e4,1e4); tic b = diag(1./diag(a)); toc Elapsed time...

6 months ago | 0

Answered
using polyval with one of the polynomials of a spline obtained with the unmkpp command, the results do not overlap! Why?
Hello TH,. spline polynomials are local to the secgment in question starting from x = 0, so if an interval is, for example 3 to...

6 months ago | 1

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Answered
Multiplication of submatrices of a matrix
Hi Laura, if I interpret this correctly, you have n rows (I'll use small letters mostly) of the form Anew = [c c*b1 c c*b2 ...

6 months ago | 0

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Answered
matrix inverse results different between r2023b and 2021b
Hi QL. you called both the inverse matrices '2021b' so I called the first one F and the second one S (and the orginal matrix is...

6 months ago | 0

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Answered
How do I get rid of these weird lines in the surf plot?
Hello Max, It appears that the GetRectGrid function creates points whose order is imcompatible with the reshape functions that ...

7 months ago | 1

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