Star Strider

Last seen: Today | Active 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. Time Zone: UTC-7 (Standard); UTC-6 (Daylight Savings/Summer)

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I Want to solve system of three differential equations numerically. How can i solve it with ode45, or are there any other ways?
syms v1(t) y1(t) y2(t) v2(t) a2(t) phi(t) L r A B C D E F G H I J beta Omega(t) Omegaac(t) omega(t) omegaac(t) Y t sympref('...

2 hours ago | 0

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import data from csv and plot it
I opened it in Excel, did a straightforward manual copy-paste to Notebook, and saved it to a text file (that I uploaded here). ...

2 hours ago | 1

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x values when taking a numerical derivative
‘I think (correct me if I'm wrong) this can be done by diff(y)./diff(x)’ Not actually wrong, simply mistaken with respect to ...

5 hours ago | 0

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Plotting surface tangent to surface plot
The code defines ‘x’ as a scalar: x=linspace(-9,0.5,1); with one element equal to 0.5. That creates ‘X’ and ‘Y’ as vectors...

5 hours ago | 0

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How do I change a date in a cell into three cells in MatLab xlsx file?
After using readtable to import the Excel file, try something like this — T1 = table(datetime('now') + days(0:4).', rand(5,1),...

1 day ago | 1

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How can i find the co-ordinates of a point where the slop is -1 in below graph ?
Try this — T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1285050/cmos.txt', 'VariableNamingRu...

1 day ago | 2

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Improve part of code using a loop
One approach — date_time = (datetime('01-Jan-2023') : caldays(1) : datetime('31-Dec-2023')).'; Values = randn(numel(date_time...

2 days ago | 0

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How to plot 2 columns (one is population the other is years) in a linear graph
This is difficult without the Excel file. Taking a wild guess: plot(Population.years, Population.Population) alternatively...

2 days ago | 0

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Unclear periodicity output with daily temperature dataset using periodogram
I have no idea what temperature is being measured. I would expect environmental temperatures to have a significantly wider rang...

2 days ago | 0

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Why is my FFT diagram has a slope approaching to zero?
It looks correct to me. I made three changes: indexing into the table and references to it, subtracted the mean from ‘S’ since ...

3 days ago | 0

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Filtering between frequency range
The function you use depends on how you want to filter them. The filtering functions (includijng filtfilt) operate column-wise ...

3 days ago | 0

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Adding scatter points to a contour plot
‘Highest’ usually implies one value, not 67, and without your data (the (67x67) matrix) and understanding what the ‘highest 67 v...

3 days ago | 0

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For each peak, I would like to calculate the delta (shown in image) for the plot in the script at each threshold level in a table.
@Rufus Adjetey — Try my code — X = [0.0318400000000000,0.0368000000000000,0.0417600000000000,0.0467200000000000,0.0516800000...

4 days ago | 0

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How to locate X value for a given Y value
In the absence of the data, getting an independent variable valuex ‘x’ from an dependent variable value ‘y’ is relatively straig...

5 days ago | 0

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How do I make a bar graph from uneven arrays without adding zeros to the end of the smaller array?
I am not certain what you want. This approach creates a NaN matrix with the column length of the larger vector, writes the or...

5 days ago | 0

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Convenient way to filter sinusoidal noise from decay data?
If you want to use a frequency-selective filter, first do a fft of the data to determine the frequency components, then use the ...

6 days ago | 0

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How to read Brimrose NIR spectral data
I have no idea what is supposed to be in that file. It appears to be a binary file, so experiment with the fread function. A...

6 days ago | 0

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How can I get a smooth curve in MATLAB?
One option is to interpolate to a finer ‘x’ vecttor, and then use a method such as 'pchip', 'spline', 'makima', or others to do ...

6 days ago | 0

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Cannot add shaded confidence intervals?
We do not have your data. The fliplr function will not produce the desired result with column data. I prefer to use the patc...

6 days ago | 0

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How to use the data from a .mat file to make a graphic?
Use the load function to ‘read’ the .mat file. (I always load into a variable as a structure of the .mat file contents so that ...

7 days ago | 0

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A way to write "if x is in y matrix do this"
It depends what the random number is, and how you define ‘y’ . The ismember function works for exact comparisons. The ismember...

7 days ago | 0

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How can I delete a specific row from a timetable?
Try something like this — LD = load(websave('TimeTable','https://www.mathworks.com/matlabcentral/answers/uploaded_files/127871...

7 days ago | 1

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Answered
How to transform a second order ODE to the format xddot=A.X+B.U
See if using odeToVectorField and matlabFunction will do what you want. Those should work if you want to solve them using the...

7 days ago | 0

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Convert uint8 vector to float
Since you apparently know the mapping, one option is to simply calculate a linear regression (assuming that a linear relation ex...

7 days ago | 1

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How do I plot horizontal time intervals and ignore others to produce a non continous dashed line plot?
Try this — tTime =[0.0547083333333333 0.0553541666666667 0.0587500000000000 0.0599375000000000 0.0632291666666667 0.0646458333...

7 days ago | 0

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How to change a single xtick (x label)?
Perhaps something like this — x = 1:100; y = rand (100); figure plot(x,y) xt = xticks; xticklabels([{'No Stim'} compose...

7 days ago | 0

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Answered
find a tangent values from plot
I am not certain what tangent (slope) you want. I am assuming it is from (0,0) to where the tangent line touches each parabols....

8 days ago | 0

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Best way for finding transfer function in time domain
If you want to create a filter from it (returning numerator and denominator coefficient vectors), use the Signal Processing Tool...

8 days ago | 0

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How to define the location/position of a number in a specific cell array?
It would help to have the actual cell array. Try something like this — MY = {[]; []; []; 1; []; []; []} loc = find(cellf...

9 days ago | 0

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How can I plot this X and Y data?
Perhaps something like this — LD = load(websave('Tide_Data','https://www.mathworks.com/matlabcentral/answers/uploaded_files/12...

10 days ago | 0

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