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Star Strider


Last seen: Today
15 860 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
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) ...

environ 3 heures ago | 0

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 ...

environ 5 heures 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...

environ 19 heures ago | 0

Answered
Adding text to each subplots
Use xlim and ylim to make the text positions relative to the axes — x1 = linspace(0,10, 25); y1 = exp(-0.1*x1); x2 = linspac...

environ 23 heures ago | 0

| accepted

Answered
Error in App Designer " Undefined function 'sym2poly' for input arguments of type 'char'.."
Apart from the app code, apparently the numerator and denominator polynomials are not being transofmred into symbolic variables....

environ 23 heures ago | 1

| accepted

Answered
How to get tfest() to focus on a frequency range (or is something else wrong)?
Without any data or code, and since I have no idea how that was plotted, the only solution I can offer is to use the compare fun...

environ 23 heures ago | 0

Answered
CIplot unable to fill on log-x axis
I am not certain what you are doing. However in many situations, it is easier to initially plot in a linear scale, then afterwa...

1 jour ago | 0

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Answered
Numerical integration using Trapz
That should produce one scalar value as ‘F’, so the subscripts are not necessary. I would do something like this — F = trap...

1 jour ago | 0

| accepted

Answered
Data is not importing? SOS
It is not importing because the correct approach to reading .wav files is to use audioread. Try that. It should do what you ...

1 jour ago | 0

Answered
unable to solve with respect to y
Try this — syms s x y(x) y0 Dy0 C1 C2 Dy = diff(y); D2y = diff(Dy); ode=(x^2*D2y)-(3*x*Dy)+(3*y)==(2*x^4*(exp(x))) y(x,C1,...

2 jours ago | 0

Answered
What would be a best interpolation method to get test data for a specific temperature?
I would just use interp1 — TestData = sortrows(randi([0 200], 15, 4),1) InterpTemps = [0 40 100]; Interp_234 = interp1(TestD...

2 jours ago | 0

Answered
xlsread isn't storing all the cell values from a column
Try something like this — T1 = readtable('YourExcelFile.xlsx', 'Range','A1:E19') That will import everything as a table, and ...

2 jours ago | 0

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Answered
Output argument "K" (and maybe others) not assigned during call to "linear_kernel".
Why not just — K = dot(x1,x2) instead? See the documentation on the dot function for details.

2 jours ago | 0

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Answered
The value of equation
I have absolutely no clue as to what you want. Try this — syms x u x3 %x = (0:1:4) L1 = 8; L =...

2 jours ago | 0

Answered
Calculating the Standard Deviation
Two options are to either calculate it directly, or use the normalize funciton — y = readmatrix('https://www.mathworks.com/mat...

2 jours ago | 0

Answered
How to Numerically Integrate Vector with Timestep
Use the trapz function (or cumtrapz, dependng on the result you want), The vector with respect to the numeric integration (time...

2 jours ago | 1

Answered
Getting the area of a surface integral from Matlab
See if simplifying it does what you want — syms phi the x = cos(phi).*sin(the); y = sin(phi).*sin(the); z = cos(the); dens...

2 jours ago | 1

| accepted

Answered
How to process xlsx with readtable for graphs/plots
One approach is to use groupsummary to aggregate the data — T1 = readtable('https://www.mathworks.com/matlabcentral/answers/up...

3 jours ago | 0

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Answered
Solve for one variable
It really is not at all different, except the format. Examing it — syms p A=0.1199; At=0.112; y=1.43; P1=119; Error =0...

3 jours ago | 0

Answered
Can you have lines between circles on a scatter plot?
Try this — a = [50:199]; b = [75:224]; i = [1:150]; scatter( i, [a;b] ) [ia,ib] = (ismember(a,b)); aidx = find(ia); hold...

3 jours ago | 0

| accepted

Answered
empty sym: 0-by-1. please help me
a=9.61; b=0.16; fc=2000*10^6; c=300*10^6; A= 10^(1/10)-10^(20/10); B=(20*log10(4*pi*fc/c))+10^(20/10) syms R real; y=...

3 jours ago | 1

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Answered
Help with Laplace ODE
Try this — syms t y(t) Y(s) Dy0 a b y0 Dy1 = diff(y,t,1); eqn = laplace(Dy1== a*sinh(a*t)) eqn = subs(eqn, {laplace(y(t), ...

3 jours ago | 1

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Answered
FFT results correct for following filtering?
It is my code ( apparently copied from is the FFT right? ) and I do not see any mistakes in it! That signal and ‘CH0’ here ar...

3 jours ago | 1

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Answered
Error in ode45 (line 115) and odearguments (line 90)
First, do not use global variables! Pass extra parameters as additional parameters. See Passing Extra Parameters for details....

4 jours ago | 0

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Answered
Fourier series using matlab
We can’t correct it because you posted an image of it rather the actual code. The solution is straightforward nevertheless — ...

4 jours ago | 1

Answered
Convert signal from time domain to frequency domain with fft
If ‘T’ (that I assume is the time vector) is regularly-sampled (constant sampling intervals), first determine the sampling inter...

4 jours ago | 0

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Answered
is the FFT right?
‘What is the meaning of the y axis?’ It is necessary to normalise the fft result by the length of the vector it uses as an ar...

4 jours ago | 1

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Answered
Homogeneous differential equation with dsolve => Warning: Unable to find explicit solution.
The differential equation is nonlinear. There are only a few nonlinear differential equations that have analytical solutions. ...

4 jours ago | 0

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Answered
how to draw a quadratic equation
It is definitely close to linear in the region you are plotting it. To plot it and see its quadratic shape, find the inflectio...

4 jours ago | 0

Answered
Solving linear system - but using only parts of the Matrix
The lsqr function is appropriate here — D = [... 0 0 0 0 0.345265357599750 0.457309520629080 0.548726230994530 0 0 0 0 0 0 0...

4 jours ago | 1

| accepted

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