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How to interface symbolic solutions with numeric ode solvers
With an initially symbolic set of differential equations, the symbolic versions should not be part of a numerical integration. ...

circa 2 mesi fa | 0

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How do I obtain the area of each contour on a contour3 plot?
I wrote some utility routines to get information from contour plots a while ago, and tweaked them for this project. The ap[proa...

circa 2 mesi fa | 0

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How to plot direction of forces on a body with polar plots or similar?
I can’t figure out what you’re plotting. The data are vectors, so any sort of surface plot isn’t possible, and I don’t understa...

circa 2 mesi fa | 1

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Can someone help me display the area bounded by the curve and the linear line. Pls see attached photo.
One approach — clear all; close all format shortG filename = 'GT+10-ubc-X-Axis - Static.csv'; T1 = readtable(file...

circa 2 mesi fa | 0

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I want to find the least negative non positive number in a vector
Perhaps this — V = [-10 , -5 , -1 , -0.1 , 0 , 1 , 2 , 3 , 4 , 5] [Vmax,idx] = max(V(V<0)) V(idx) .

circa 2 mesi fa | 1

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Plot Piecewise function graph
To do this in the Symbolic Math Toolbox, just write it essentially as in your original post — syms x f(x) = piecewise((-3*...

circa 2 mesi fa | 0

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Surf plot from excel file
It would help to know what the data are, and what you want to do with the NaN values. That aside, just plot all but the firs...

circa 2 mesi fa | 0

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How to Curvefit amplitude output of a spring-mass-damper system to find coefficients?
Try this — load('sampleData.mat') % whos objfcn = @(b,t) b(1) .* exp(b(2).*t) .* cos(2*pi*b(3)*t + b(4)) + b(5); Lvlm =...

circa 2 mesi fa | 0

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Using string variable names for dot indexing
That approach can work, however it is necessary to put the variable name from the cell array in parentheses — varnames = {'rs...

circa 2 mesi fa | 0

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Normalized graph not showing
The timeseries ‘out.Q_i_nd.Data’ is a 3D matrix. You need to use the squeeze function to remove the extra singleton dimensions. ...

circa 2 mesi fa | 0

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I am trying to plot a graph of two variables z1 and z2 versus t. but for some values of t I am getting z2 values negative in a graph. How to make these z2 values zero?
One approach — z2 = randn(1,10) z2(z2<0) = 0 .

circa 2 mesi fa | 0

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Want to truncate an array
There are a few options, including using the vpa function in the Symbolic Math Toolbox, and to use sprintf to display the values...

circa 2 mesi fa | 0

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bug in sprintf 2024a, can't use other variable and just repeating the first variable
The residue funciton produces column vectors in its output. To use sprintf with them, concatenate them in a matrix and then tra...

circa 2 mesi fa | 0

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Graph lines not showing
See if the yline function will do what you want.

circa 2 mesi fa | 1

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Two sets of data with two date ranges and y-axis values
Try this — x1 = 1:250; y1 = 20*sin(2*pi*x1/100) + 20 + randn(size(x1))*5; x2 = 15:250; y2 = cos(2*pi*x2/150)*60 + 150 + ...

circa 2 mesi fa | 1

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Parameters identification providing derivative
The differential equation needs to be integrated in order to use . This does not appear to be as straightforward as I would hav...

circa 2 mesi fa | 1

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How to use values from excel file in genetic algorithm
Use the readmatrix function instead of readtable since there are no variable names. It produces a matrix that can be address...

circa 2 mesi fa | 1

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How to do fft of a csv file to plot amplitude spectrum
See the documentation for both fft and nufft. One of those should apply to your problem. Another optioon is the pspectrum fu...

circa 2 mesi fa | 0

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Parameter estimation of SEIHRDBP model
The time values are incorrect. The complete table of those values should be — Date Infected Death ____ ___...

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Fitting an custom equasion where i only want to optimize specific parameters
You would need to supply pre-determined values for ‘sigk’, ‘h1’, ‘g1’, and ‘Dwir’ if you have them (you have already calculated ...

circa 2 mesi fa | 1

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Grid in MIMO nyquist diagram
I am not certain what you want to do or how much of the documentation you have explored. Most of the Control System Toolbox a...

circa 2 mesi fa | 1

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Fittype issue: unrealistic results and problems with upper and lower bounds
The bounds may not be set correctly. Note that while ‘a’ is supposed to be between 0.1 and 1, your bounds for it are between 10...

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Parameter estimation of SEIHRDBP model
Thank you for quoting my code! The problem was here: c0=theta(end-3:end); use this instead: c0=theta(end-7:end); Since m...

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unable to plot semilogy properly
The easiest way to solve that is to plot each curve on its own y-axis using the yyaxis function — % QPSK M = 8; k = log2(M)...

circa 2 mesi fa | 0

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datetime don't displays the correct order
The 'InputFormat' and 'Format' name-value pairs are not the same. You need to specify them separately — aaa=datetime(dataa,...

circa 2 mesi fa | 0

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How to get daily max, min, and mean from a timetable?
Your groupsummary call is correct, except for not putting the data variables in square brackets (or curly braces). With that...

circa 2 mesi fa | 0

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I'm unsure of why there is an error on F=@x
The statement order is reversed from what it should be — f=@(x)exp(-0.5*x)*(4-x)-2; df=@(x)exp(-0.5*x)*(-3+0.5*x); Xs = n...

circa 2 mesi fa | 1

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small floating point has been considred as zero value!
Your code works correctly when I run it here — x=0.16 if x>0.1 d=1 else d=0 end d .

circa 2 mesi fa | 0

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Find Area under the curve as a non negative
It would help to have the data. Perhaps selecting everything with both x and y coordinates greater than zero, and then integr...

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Transparency in scatter plot
It would help to have representative data. I suspect the vector you are using as ‘C’ has very low positive values (perhaps on ...

circa 2 mesi fa | 0

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