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# Star Strider

##### Last seen: Today
13 289 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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How to take a derivative of x with respect to time.
I am not certain what you want to do. If you have R2015a or later, use the functionalDerivative function: syms x(t) y(t) z(t)...

20 minuter ago | 0

how to find duration of peak; starting and ending points
Experiment with ths ischange function, and if you have the Signal Processing Toolbox, the findchangepts function.

ungefär 12 timmar ago | 0

Global optimization of parameters in ode
See: Is it possible to use Simulated Annealing or Genetic Algorithm for parameter estimation of a parametric System of ODEs? for...

ungefär 16 timmar ago | 0

Change color of graph at a certain value (temperature vs. time)

ungefär 16 timmar ago | 0

Obtain single equation from a system of equations stored as an anonymous function
Not directly. I would do this: F = @(x) [x(1).*x(2).^2 + sin(x(2)) ; ... cos(x(1)) + x(2).^3 ] ; z = [2 6];...

ungefär 20 timmar ago | 0

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Error using @regress fuction
Try this: func = @(Q)regress(Q,X); then call it as: [b,bint] = func(Change1.ReturnsCleaned); (It seems a bit inefficient...

ungefär 21 timmar ago | 0

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MATLAB: solving a 2nd order ODE which has a parameter which evolves in time
Try this: syms k(t) y(t) % Declare ‘k(t)’ Here [System,Subs] = odeToVectorField(...

ungefär 21 timmar ago | 0

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Overlap of 2 logicals
Since ‘B’ and ‘B2’ have not yeat appeared, try this with synthetic versions of them: B = randi([0 1], 5, 6) > 0 B2 = randi([0...

ungefär 22 timmar ago | 0

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How to make plot more visible in matlab
See the plot documentation section on Specify Line Width, Marker Size, and Marker Color. That should get you started.

ungefär 23 timmar ago | 0

Solve a second-order differential equation with constant parameters changing through an external parameter
It appears that what you want to do is to pass your data to your ODE function ‘fx’. See the documentation section on Passing Ex...

en dag ago | 2

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getting z transform in factored form?using Matlab?
Control System Toolbox: z = tf('z'); H = (4*z^2 + 3*z + 9) / (4*z^2 + 3*z - 4); zsys = zpk(H); Z = [zsys.Z{:}] P = [zsys.P...

en dag ago | 0

How do I use the "omitnan' option for the Mean function when calling the function using the splitapply function?
One option: splitapply(@(x)mean(x,'omitnan'),MyArray,G)

en dag ago | 0

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Print figure without its title
One option is to keep the title in the figure call. See Specify Figure Title for an example. Another option is: title('Ran...

en dag ago | 0

Error calling a function or indexing a variable, apparently the first line for plotting is wrong, can't figure out whats wrong with it...
The ‘error’ function needs to be defined as an anonymous function, and ‘y’ needs to be the same size as ‘c’. Try this: erro...

en dag ago | 0

plotting a polinomial fraction over a strict range
I do not have the DSP System Toolbox, so I do not have tfplot. Try this instead: q=[1 1]; d=[1 1 1]; x=0:0.001:3; trf ...

en dag ago | 0

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Finding points with same y-value on a graph.
Try this: x = [2,4,7,9,10,14]; y = [5,10,15,14,12,3]; new_y_value = 12.5 [~,idx] = max(y); newx(1) = interp1(y(1:idx), x(...

en dag ago | 0

I want to do the correlation of the following two plots
Going back to using my code (because it is easier to work with): Ts=1/200e6; t=Ts:Ts:0.00005; y=[ones(1,2000) zeros(1,8000...

2 dagar ago | 1

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system of 3 equation with 3 unknown, with two 2nd order equation
The resuillts are strictly numerical (not containing symbolic variables), so use vpasolve instead of solve: syms QV3 QV2 QVl ...

2 dagar ago | 0

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how to solve this complex equation in matlab?
Try this: syms theta gama Eqn = exp(pi/4*i)*(5+15i)+exp(i*theta)*(25+5i) == 40+exp(i*gama)*(-10+20i); [theta,gama] = vpasol...

2 dagar ago | 1

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removing all rows with duplicate information in two columns
Try this: a=[1 2 3 4 5; 1 3 4 5 6; 1 2 3 5 5]; [~,~,idx] = unique(a(:,[1 5]),'rows'); tally = accumarray(idx,(1:numel(idx))....

3 dagar ago | 0

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How to delete a whole table in the matlab?
tablename = [];

3 dagar ago | 1

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How can I separate the arrays when making a table?
Try this: n = 5; A = rand(n,1); B = rand(n,5); T = array2table([A, B]) That should do what you want.

3 dagar ago | 1

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how to combine date and time
In theory at least, datetime should be able to do this seamlessly using the timeofday function for the seconds. In practice, it...

3 dagar ago | 0

What am I doing wrong? Matrix operators
If you want to raaise the elements of a matrix to a power, use element-wise exponentiation with the dot operator: .^ and see: Ar...

3 dagar ago | 0

I can't plot a function I created with respect for time
You need to code it as an anonymous function. See Anonymous Functions for details. Specifically: x = @(t) X.*(exp(-Zeta.*...

4 dagar ago | 0

Error when solving system of equations with ode45 in MATLAB R2019b
The system contains only two derivatives, and . It appears that ‘u’ and ‘z’ are either functions that need to be evaluated, or...

4 dagar ago | 1

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How to plot a function that relies on another function?
Since ‘A’ is a function, it must be evaluated in order to use its results. Try this: A = @(y) y*2; X = @(y) A(y)+10; f...

4 dagar ago | 0

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How to make this signal linear
If you want to eliminate the low-frequency parabolic(?) trend, the easiest way is to use a digital filter: signal_2 = load('si...

5 dagar ago | 0

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