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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Answered
how to import file?
Try this — Files = dir('*.csv'); Filesc = struct2cell(Files); NrFiles = size(Filesc,2) for k = 1:NrFiles filename = ...

22 hours ago | 0

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How to interpret the frequencies on a symmteric FFT plot.
You need to use the fftshift function to put the zero frequency (D-C or constant offset) value in the centre. Then, depending o...

23 hours ago | 0

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Answered
How to find the coordinates of contours when they go out of bounds and form multiple contours?
Here is my approach to this — load('contours.mat') pk = -32; [c2] = contourf(x2,y2,z35b, [pk pk] ,'ShowText','on',FaceAlpha...

24 hours ago | 0

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How to combine columns from large dataset to datetime with correct vector or doublestring?
Use curly brackets {} instead of parentheses when referring to numbered table variables — Date=datetime(dataTable{:,3:5})+hour...

1 day ago | 0

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How can I selectively multiplying the negative values with (-1) in an excel file?
Multiplying the negative values of column 2 by -1 will of course create them as positive values for all the entries. Use the ...

2 days ago | 1

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How to estimate Y using a linear regression and an uncertain X value.
If I understand corectly what yoiu want to do, the best approach might be to use fitlm and then use the appropriate predict func...

2 days ago | 0

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Why does expm command work too slow?
If you want to multiply it by scalar or vector ‘t’, create an anonymous function rather than doing it symbolically — A_aug = r...

3 days ago | 1

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How to draw a semi circle filled with jet color (like in the image) ?
Try this — N = 250; th1 = linspace(pi, 3*pi/2, N); r = linspace(0, 1, N); z = r; x1 = r(:)*cos(th1); y1 = r(:)*sin(th1)...

3 days ago | 0

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Time-dependent parameter in ODE solver
The interp1 use in the documentation section for time-dependent parameters refers to vector arguments with a dependent variable ...

3 days ago | 0

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Connecting different sets of 3D points
I assume the rows are the (x,y,z) coordinates, If so, try this — A_3Dpts= [-0.91, 0.53, 0.32; -.88, .51, .3; -.84, .43, .16...

4 days ago | 1

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Answered
How do I perform several iterations in MATLAB?
Since ‘y’ appears to be a column vector, the loop is not necessary. Just use: L = 1.56*(y.^2)*tanh(61.58/L); If you are loo...

4 days ago | 0

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Answered
How do i find x from given y that is closest to my peak or at x=0?
One approach — x = linspace(-10,10,500); y = 1 - x.^2; L = numel(x); yval = -6; zxi = find(diff(sign(y -yval))); for ...

4 days ago | 0

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Answered
Symbolic function Gaussian Beam
You need to use element-wise operations. See the documentation on Array vs. Matrix Operations for details. Also, you can use...

4 days ago | 0

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Using repelem to vertially concatonate non-numeric variable
I am not certain what you want to do, however the repmat function might be a better choice, since it allows the dimensions to be...

4 days ago | 1

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Is using alphabetical characters in the area (x,y) syntax possible?
‘Is using alphabetical characters instead of numeric arguments as x-variables in the area (x,y) syntax possible?’ Yes, in the...

4 days ago | 0

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How to plot Rankine Half Body Streamlines
I can’t run that because the relevant data aren’t provided. Tha atan calls could be the problem. Substituting‘atan(y/x)’ with ...

4 days ago | 1

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Matlab - inputs must be scalar when using linspace
The problem is that the original ‘i’ value in each loop returned a vector, and that vector became the subscript for the ‘velocit...

5 days ago | 0

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solve not working for symbolic equation
When in doubt, plot the function. The ‘ib’ function has a minimum value of -146.3 and a maximum of -28.2. It never crosses...

5 days ago | 0

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How to know exactly what row (or index number?) in a table based on user input?
The file posted in your previous Question had only time values. Assuming the data you refer to here is different, the matchin...

6 days ago | 0

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Voltage find equation diagramm
Perhaps this — imshow(imread('LI.jpg')) T1 = readtable('Versuch.txt'); T1.Properties.VariableNames = {'Time','Voltage'} ...

6 days ago | 0

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Answered
My calculation for respiratory rate shows the same bpm for my 3 waveforms.
Perhap;s this — LD1 = load('USaverageImageIntensity_R1.mat'); Corr(:,1) = LD1.Corr; LD2 = load('USaverageImageIntensity_R2.m...

6 days ago | 0

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Add initial conditions when using laplace function
That requires a subs call for each equation. (The sympref call here makes this easier. You can remove it later if desired.) ...

7 days ago | 1

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3D plot two curves
Perhaps something like this — p = linspace(-pi/2, pi/2, 50)+pi/2; x1 = cos(p); y1 = 1.01*sin(p); x2 = cos(p); y2 = 0.99*...

7 days ago | 0

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Answered
Create a fit for data with a polynom first degree
I would expect R² to be 1 (or close to it) if a lilnear model is a perfect firt to the data. Using fitlm — x = [0.1201 0.13...

7 days ago | 0

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Answered
unable to plot columns of multiple cells
Logarithms of time variables do not actually exist (probably anywhere), however there are ways to get round that problem. Thi...

7 days ago | 1

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how to fit the coupled differential equations and get the coefficients?
See: Parameter Estimation for a System of Differential Equations (and similar posts) for an easy way to estimate the parameters....

7 days ago | 0

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Trouble using the ode45 input
The call to ‘f’ in the ode45 call (and the correct ode45 call) should be: [t,Y] = ode45(@(t,y)f(t,y,omega0), [0, 15], [y0,v0])...

7 days ago | 0

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Entry and exit points / trajectories through a rectangle (orbits)
This should be a relatively straightforward interpolation problem in that the only calculations necessary should be to first fin...

8 days ago | 0

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calculate boolinger bandwidth using matlab function
The std2 function takes the standard deviation of all the elements in an array (it only has one argument, that being the entire ...

8 days ago | 0

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Answered
strange behavior of plot and freqz
Thje angle functon returns angles in radians. If you add a call to the rad2deg function, the results will be in degrees, and t...

9 days ago | 0

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