# David Goodmanson

Last seen: Today Active since 2012

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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...

10 days ago | 0

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...

10 days ago | 0

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)) ...

13 days ago | 0

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...

19 days ago | 1

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...

25 days ago | 0

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...

25 days ago | 1

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...

1 month ago | 0

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...

1 month ago | 0

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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...

1 month ago | 0

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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 ...

2 months ago | 0

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...

2 months ago | 1

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...

2 months ago | 0

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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...

3 months ago | 0

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...

3 months ago | 1

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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 ...

3 months ago | 0

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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...

3 months ago | 0

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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 ...

3 months ago | 1

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Error in ode45 solution
Hello PS, Assuming the following (before variables get changed around) tv_jk = tv_kj, for all j,k all real de...

3 months ago | 0

reproduces the audio signal after sampling!!!
Hello Vu & Paul, < I took a brief look at the Vaidyanathan.paper and although the decimation process seems clear enough, the 'i...

4 months ago | 1

Matlab got this wrong: Limit as n goes to infinity: (1+(i/n))^(n^2). Matlab says it's exp(2), which is wrong. Pls confirm.
Hi Moses, not every expression has a limit, or should. That's the case here, as anyone can check. For large n the function zi...

4 months ago | 1

Is there a way to create a lot of graphs for a 4D matrix without coding for a ton of individual graphs?
Hi Kitt, Here is one approach. In the example you are using imagsc plots instead of e.g. 1d plots of some state quantity vs. t...

4 months ago | 1

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How can I calculate the integral of associate LegendreP(1,n,theta)*cos(theta)^2 ?
Hello Se, First of all I think you probably mean the integral of P(1,n,cos(theta))*cos(theta)^2 which is what makes sense whe...

4 months ago | 0

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How to solve swallowtail integral
Hello YM, You won't be able to solve this as a closed form function of X,Y,Z but you can find the integral for given values of ...

4 months ago | 0

Trying to ubderstand the power distribution in fft plot
Hello Yogesh, The fact that all the abs(peaks)^2 add up to the expected total is just Parseval's theorem and has really nothing...

4 months ago | 1

How to interpret the amplitude of impulse() results
Hi HG, the large ampltude of the impulse response is correct. (has the original question been edited?) This has to be the cas...

4 months ago | 0

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Find intersections of two sin wave function
Hello ZH The symbol f is a bit overused in your example, but if you have two functions g1 = A*sin(2*pi*f1*t +phi).^2 g2 = A*...

5 months ago | 0

Struggling to decide the sampling frequency for this fft plot
Hi Yogesh, If the time array has spacing delt (which you denote by dt) and the frequency array has spacing delf, then for an N-...

5 months ago | 0

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Why is my 3D Projectile Trajectory not being calculated properly?
Hi Abeljohn, I think the only real issue here is trying to view the trajectory in plot3, If you let the ground be the xy plane...

5 months ago | 1

When this code is executed, 36 separate windows will open. I want the result to be displayed in a window.
Hi Babr, I think this is basically what is intended, taking the plot out of the for loop. close all; clear; clc N = 2048; ...

5 months ago | 0

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