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Star Strider


Last seen: Today
13,974 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
Contaminate an EMG with 50 Hz signal
I have no idea what ‘isn’t working’ means. This version of your code works: Fs = 256; ...

5 hours ago | 0

| accepted

Answered
How to color individual points on errorbar plot?
You need to plot with respect to an independent variable. Try this: means=[1 1 2 3 4]; standarddeviation=[0.1 0.2 0.2 0.3 ...

8 hours ago | 0

Answered
displacing iterations of a signal
I am not certain what you want to do. If you want the different waveforms to appear consecutively, plot them against an indepen...

19 hours ago | 0

Answered
How can I plot shaded confidence intervals on my plot?
Add these two patch calls after the last plot call and before the hold off call: patch([x fliplr(x)], [y-CI fliplr(y+CI)], [0,...

1 day ago | 1

| accepted

Answered
how to obtain the frequency when doing the fourier trasform
Assuming that the data are regularly sampled, so that the sampling intervals are the same for all of them, I usually do somethin...

1 day ago | 0

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Answered
Month as a two digit number
To have leading zeros, it has to be a character array or string variable. Try this: Date = datetime('now'); mth = sprintf(...

1 day ago | 2

Answered
Designing a fir filter and how to apply it to a signal
You need to normalise the stopband frequencies by the Nyquist frequency. Try this: Wn=[fp1 fp2]/(fs/2); That worked when I...

1 day ago | 0

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Answered
Energy calculation via current signal integration with limits
Add this after your posted code: idxrng = iVs:iVe; IntP = cumtrapz(T(idxrng), P(idxrng)); figure subplot(3,1,1) yyaxis l...

1 day ago | 0

| accepted

Answered
Contour plot of data on a non-rectangular xy domain
I am not certain what you want. Try this: X = [0.940727422583647 1.07008276356436 1.22692065834036 1.36057673106938 1.47757...

1 day ago | 0

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Answered
Position and extraction of row
It would definitely help to see what ‘mergetable1’ is, and how you are getting ‘AccelSN’. If ‘AccelSN’ is read as a string (f...

2 days ago | 0

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Answered
signal fourier transform include unit step function
Try this version of your code: syms t x(t) % t = linspace(-20, 20, 5000); % u = @(t) (t >= 0); x(t) = exp(-t) * heaviside...

2 days ago | 0

| accepted

Answered
Matlab dsolve function issue with format.
My (R2020a) version requires slightly different symbolic convetions. Try this: syms x(t) Dx = diff(x); D2x = diff(Dx); e...

2 days ago | 0

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Answered
Extraplotation of impedance data
First, I doubt that extrapolating from 250 kHz to 10 MHz is appropriate in any event. However it could be, if you identified ...

2 days ago | 0

Answered
Why I can't use the function of decimate
I get the same result as in the documentation (in R2020a). First, what version of MATLAB are you using? The current online d...

2 days ago | 0

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Answered
determine the R waves to evaluate the ECG signal and determine the heart rate.
Use findpeaks or islocalmax to locate the R-wave peaks.

2 days ago | 0

Answered
Rolve function around axis to create 3D surface.
See: Plotting an exponential exp(-x), in 3D? for an example.

3 days ago | 1

| accepted

Answered
Error using ss. How do i fix this?
Transpose ‘BS’ to a column vector (everywhere you use it, since you re-define it): BS=[0 0 0 0 0 0 k4/m4 0].'; Do the same f...

3 days ago | 1

| accepted

Answered
Initial Conditions for first derivative defined as a transfer function
Apparently, step does not allow initial conditions to be stated, however initial does, and produces an impulse response plot giv...

3 days ago | 0

Answered
turning functions into floating-point numbers
Your question lacks detail. If you have an expression in one or more variables, you can express it as a function (most likely a...

3 days ago | 0

Answered
need help on nomenclature, Simplify symbolic variables
If simplify is not simplifying to the extent that you want it to, use the Steps name-value pair to tell it to keep simplifying u...

4 days ago | 0

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Answered
create yyyymm variable from date
Try this: dt = '1/1/2020'; Out = datetime(dt, 'InputFormat','MM/dd/yyyy', 'Format','yyyyMM') producing: Out = dateti...

4 days ago | 0

| accepted

Answered
Resampling Data using Interp1
You are doing signal processing. For that, use the resample function. It will do the interpolation, and will also use an anti-...

4 days ago | 0

Answered
Can ode45 be used to solve mx'' + cx' + kx^1.1=0 x(0)=5;x'(0)=0? Getting complex numbers in answers.
You need to plot the real and complex parts separately. Assuming: [t,y] = ode45(yourOdefcn, tspan, ic); plot it as: fig...

4 days ago | 0

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Answered
How to show numeric solution instead of symbolic solution
The ‘q_dot’ variable cannot be expressed as a strictly numeric array because it contains symbolic variables. The best you can...

4 days ago | 0

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Answered
Jacobian matrix of a numeric matri
See if the gradient function will do what you want. That is likely as close as you can get for a numeric matrix. If it is a ...

4 days ago | 0

Answered
Second Order ODE with Power
The best way to integrate it numerically is something like this: syms x(t) A B C D vb b Y t v=diff(x,t,2)==(A/x)*(B+C*(diff(...

4 days ago | 0

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Answered
Running data through a filter multiple times
It is not easy to follow what you are doing here, especially with respect to your using the strings as part of the subscript (th...

4 days ago | 1

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Answered
How to correctly apply bandpass filter to EEG data?
The bandpass function (and its friends) in my experience have all used filtfilt to do the actual filtering, so there should not ...

4 days ago | 0

Answered
findpeaks returns wrong width
If you have the Signal Processing Toolbox, use the pulsewidth function for this: D = readmatrix('test.csv'); A1 = D(:,2); t1...

5 days ago | 0

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Answered
genetic algorithm for curve fitting
I would do something like this (with ‘M’ and the constants already existing in your workspace): MFit = @(c0,M0,h,z,z0) (M0 + c...

5 days ago | 1

| accepted

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