Star Strider

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15,917 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

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Answered
Perform inverse weighted least squares regression
‘Would this be 1/error of each point?’ That would appear to be a reasonable approach, since the data with the smallest errors...

3 hours ago | 0

Answered
Finding the frequency and the phase shift of a Sin signal
One option is described in Curve fitting to a sinusoidal function and a version that could be more appropriate to your problem ...

5 hours ago | 1

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Find all possible ordered pairs that satisfy a linear equation
The ‘all possible’ criterion would produce infinite solutions. I suspect you would spend the rest of your life calculationg it!...

5 hours ago | 0

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cell2table is not recognizing certain columns (not all) containing double data
I am not certain what the problem is with readcell, however unless it is absolutely necessary to use it, use readtable instead, ...

8 hours ago | 0

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Simulation of drug distribution with ordinary differential equation
The syntax was not passing the parameters correctly to ‘ode_ex’, and was not passing to correct arguments, at least from what I ...

8 hours ago | 0

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What is a more efficient method of increasing non-zero entries by one
I am not exactly certain what you want to do, however it is straightforward to do this using logical indexing — R = [0, 0, 4, ...

8 hours ago | 0

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is poctave function working ?
The code you posted runs correctly in R2021a, since it runs correctly in the online Run feature here that uses it — Fs = 44.1E...

11 hours ago | 0

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Undefined operator '*' for input arguments of type 'categorical'.
I am not certain what the problem is, and some information is not available. Try something like this — sample = readtable('...

11 hours ago | 0

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Export/Copy Plot Line Values
Try siomething like this — x = 0:10; y1 = x.^2; y2 = 50*sin(2*pi*x/10)+50; figure hp = plot(x, y1, x, y2); Line1X = hp...

23 hours ago | 1

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Answered
Matlab plotting from a data table.
Something like this — T1 = readtable('Your CSVFile.csv'); figure plot(T1{:,1}, T1{:,2}) % Plots Th...

1 day ago | 0

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Error in multiplying corresponding elements in two matrices
It is often confusing to use ‘l’ (lower-case letter ‘L’) and ‘1’ (number ‘1’). I suspect that is the problem.

1 day ago | 1

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Answered
Find difference between two measurements
Without knowing what the data are, one option would be to use interp1 to determine the same values at specific times. I have ...

1 day ago | 0

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Solve 3 unknown variable system of equations
There are likely an infinity of solutions. Also, for whatever reason, the solve function does not like ‘L6’. A numeric a...

1 day ago | 0

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Error using sym>convertChar (line 1537) when solving an ODE using laplace transform. How to fix the problem?
Eliminate the single quotes, use double equal signs in the symbolic expression, express ‘x’ as ‘x(t)’ in the syms declaration (o...

2 days ago | 0

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Curavture/Slope Filtering
One approach could be to look for changes in the slope (using the gradient function here) with respect to the number of elements...

2 days ago | 0

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How can I find the heart rate and R-R time interval for ECG Signal?
Getting the information from the file was something of an adventure! I likely could have done this with detectImportOptions, ho...

2 days ago | 0

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Help me with Graph plot
One approach — syms x y = 6*x^3 - 37*x^2 + 37*x - 10 figure fplot(y) grid .

2 days ago | 0

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Solve the 2-nd order differential equations y"+2y'=3x
One approach would be to do this symbolically and solve it using the dsolve function.

2 days ago | 0

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Answered
Error with ode45
Supply the ‘t’ argument even if the code does not use it. Try this — t=[0 5]; inity = 1; [t,y]=ode45(@f, t, inity); plot...

3 days ago | 0

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Answered
Data import and Header Line
There are several ways to do this, likely the easiest is to use the readmatrix function (introduced in R2019a).

3 days ago | 0

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Answered
Error while using cellfun with a function
Try this instead — RRTrain1 = cellfun(@(x)RRfeatures(x),XTrain,'UniformOutput',false); I have no idea if that will do what yo...

3 days ago | 1

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Answered
Strange curve fitting with large polynomial degrees when using polyfit
As a general rule, a polynomial fit with a degree grater than 7 is likely not appropriate, so a 100 degree polynomial is giving ...

3 days ago | 1

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How to group companies by SIC codes
The discretize function could be appropriate for this.

3 days ago | 0

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3D plot from excel
Try something like this — T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/616758/Shear%20stress...

3 days ago | 1

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Answered
Adding a single number to an entire matrix
Exactly as you wrote it! a = 5 b = [1,2,3;4,5,6;7,8,9] c = a + b Use square brackets [] to code vectors and matrices.

3 days ago | 0

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Frequency domain and time-frequency domain for sae data
The pspectrum function can likely help with this, specifically with respect to the time-frequency plot.

4 days ago | 0

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Help with conditional statement
My approach to these problems is to take advantage of MATLAB’s logical vectors. So for example, if I wanted to construct a fu...

4 days ago | 1

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Add constraints to nonlinear multiple data sets fit
The nlinfit function will not allow parameter constraints. Use lsqcurvefit for that instead. Note that it is then possible t...

4 days ago | 0

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Answered
Use input from an array in a function
The ‘plan’ array is not being passed to your function, and since the function has its own workspace (that it does not share with...

4 days ago | 0

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Answered
Solving state space equation by ode45
The MATLAB ODE solvers are adaptive, and so will solve with as narrow a difference in the time steps as necessary to produce a s...

4 days ago | 0