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Star Strider


Last seen: Today
15,887 total contributions since 2012

Hic sunt dracones!

PROFESSIONAL: Physician (M.D.): Diplomate of the American Board of Internal Medicine; M.Sc. Biomedical Engineering: Instrumentation, Signal Processing, Control, System Identification, Parameter Estimation

NON-PROFESSIONAL: Amateur Extra Class Amateur Radio Operator; Private Pilot, Airplane Single Engine Land, Instrument Rating Airplane; Gamer

NOTE: I do not respond to emails or personal messages, unless they are about my File Exchange contributions.

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Answered
Counting amount of digit occurrence in a cell
Try something like this — CellArray = num2cell([2; 2; 2; 2; 2; 2; 2; 3; 9]); [Uc,~,ix] = unique([CellArray{:}],'stable'); Co...

2 hours ago | 1

| accepted

Answered
How to get z-score from Kruskal Wallis test.
See if the norminv function will do what you want.

3 hours ago | 0

Answered
Is there a way to "Save" a link to a MATLAB Answer?
You can Follow them. I save the ones I find particularly interesting (including some of my own) as Bookmarks (Firefox) in dif...

5 hours ago | 2

Answered
findchangepts use for multiple files
That’s actually not how findchangepts works (or at least is designed to work as I understand it). It finds changes in a signal ...

12 hours ago | 0

Answered
Interpreting FFT Graph with Noise Floor
Try this — X = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/613760/tapedata.csv'); t = readmatr...

23 hours ago | 0

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Answered
How to plot concentration Hb?
Use the bar and plot functions. The cross-hatching is not a standard option, so it will likely be necessary to simply use sol...

1 day ago | 0

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Answered
i have Question about Inverse lapalce transform & plot
Try this — syms s R = 1/s G = 75/(s)^2+10.25*s+100.65 F = R * G a = ilaplace (F) % x = t t = [0 10]; y = a; fplot(y,t)...

1 day ago | 0

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Answered
Changing size label in xline
Try this — x = linspace(0,6,100); y = exp(x); plot(x,y) hxl = xline(4.5,'-',{'Acceptable','Limit'}); x = linspace(0,6,...

1 day ago | 0

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Answered
Is there FWHM function in frequency domain
Try it — a = 2; p = @(t) exp(-(a*t).^2) t = linspace(-5,5); figure plot(t, p(t)) grid P = fft(p(t))/numel(t); Ts ...

1 day ago | 0

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Answered
How to use 'trapz' command in a foor loop
The problem is that ‘S_v’ has only one non-singleton dimension (i.e. it is a vector). That is throwing the error. Chan...

1 day ago | 0

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Answered
Matlab solves differential equations but returns empty plots
It is not possible to do anything with the images provided. Perhaps something like: Fds = vpa(Fds) figure fplot(Fds) a...

1 day ago | 0

Answered
How to rotate 3D surface matrices
It depends on what you want to do. To rotate the surface in the axes, use the rotate function. To change the viewpoint (ca...

1 day ago | 0

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Answered
Plot discrete fourier transform of a sine wave
Try this — f = 6000; fs = 16000; w = 2*pi*(f/fs); N = 50; n = 0:N; y = sin(w.*n); subplot(2,1,1); stem(n,y); f = -...

1 day ago | 0

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Answered
Develop a cleaner stem plot (Magnitude Spectra)
These are two-sided fft plots. I’m not certain what ‘cleaner’ is in this context, however using the fftshift function, then c...

2 days ago | 0

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Answered
How to solve Coupled Differential Equations
Try this — syms x(t) y(t) x0 y0 Dx = diff(x); Dy = diff(y); ode1 = Dy-Dx == 2 - x ode2 = 2-Dy - Dy == 3 + 2*y S = dsolve...

2 days ago | 0

Answered
How to interpolate a matrix ?
Try this — M=[ 3.2 5 4.1 4 5.6 3 6.7 ...

2 days ago | 0

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Answered
Vector counting syntax help?
Try this — A = [1 1 1 1 2 3 3 5 5 5 5 6 6 7]; [Au,~,ix] = unique(A,'stable'); Count = accumarray(ix,1); Result = table(Au(:...

2 days ago | 0

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Answered
How to get multiple variables in 'assume' ?
Declare them in the syms call as positive. MATLAB defines positive as values greater than 0. See the documentation section o...

2 days ago | 0

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Answered
signal does not show filtered, using filter()
Use freqz to see what the filters are actually doing — Fs1 = 500; %Sampling Frequency ync = [.25, .5, .25]; ync1 = [-.085 ....

3 days ago | 0

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Answered
Trying to fit parameters for an ODE model to real data using lsqcurvefit
‘... I can't seem to find any real differences between the code I've constructed and that example.’ I agree that the initial ...

3 days ago | 0

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Answered
how take a mathematical function from user
I would use the inputdlg function — prompt = {'Enter f(x,y):', 'Enter g(x):'}; response = inputdlg(prompt) f = str2func(['@(...

3 days ago | 0

Answered
Characteristics of a step response plot
Try something like this (using a transfer function from the documentation) — sys = tf([1 5 5],[1 1.65 5 6.5 2]); stinf = step...

3 days ago | 0

Answered
I want to separate the signal from the noise with the help of a low pass filter.
I could not figure out which of those signals you want to filter, so I arbitrarily chose ‘t1’ and ‘y1’. They are not consiste...

3 days ago | 0

Answered
How to change X axis in the form of percentage
Try something like this — x = linspace(77, 146); y = -60 - 15*sin(2*pi*x/50); figure plot(x, y) Ax = gca; xt = Ax.XTick...

3 days ago | 1

Answered
Plotting a filter as a function of cyclic frequency using freqz()
Your approach is correct. The reason the freqz plot did not look correct is that you were passing the filtered signal to it, no...

4 days ago | 0

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Answered
Coupled second order differential equation
Start by writing the equations using the Symbolic Math Toolbox. Specifically, see the documentation on the dsolve function. ...

4 days ago | 0

Answered
ode45 not working
There are a few errors, all easily solved. Try this — m = 5; g = 9.81; r = 0.470; I = 0.37; ks = 0.012; dt = 0.01; ...

4 days ago | 0

Answered
How to tell matlab that y is a function of x; not a constant
In the initial syms call, declare ‘y(x)’ instead of ‘y’ — syms x y(x) z z=x*y; Dz = diff(z,x) ...

4 days ago | 1

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Answered
Locating rising peaks of variable amplitude pulses
I am not certain what you are doing, or what the ‘overlaid pulses situation’ means. There appears to be a significant amount ...

4 days ago | 0

Answered
How do I make a low-pass filter on this data set?
For an EKG, use the bandpass function with the lower cutoff at 1.5 Hz and the upper cutoff between 45 Hz (if there is mains or p...

5 days ago | 0

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