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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.

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Answered
Number of line for fcontour
A somewhat different approach — syms x y z(x,y) = exp(-(x-5)^2) + cos(y) figure hfc = fcontour(z, [0 10 -2*pi 2*pi]);...

12 hours ago | 0

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Answered
ho to find index at which the 50% of the sum vector is included?
A least-squared-difference approach works — a=[3 5 7 3 5 8 9 3 1 41 6]; suma = cumsum(a); suma50 = suma(end)/2; [minv,idxv]...

14 hours ago | 1

Answered
How can I skip the first to lines from a text file and proceed to read the file with header lines in between the values?
Try this — C1 = readcell('https://www.mathworks.com/matlabcentral/answers/uploaded_files/814274/BSH_HBM_tracer_productgrid_f...

19 hours ago | 0

Answered
How to activate the low-pass filter on NI-6115?
It will likely be best to Contact Support for this. I did an online search and could find no previous posts regarding the NI-61...

23 hours ago | 0

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Answered
Function value and YDATA sizes are not equal. Can anyone help?
The problem is the randn call. With one argument, it creates an (nxn) matrix, not a vector, so of course the sizes will not mat...

23 hours ago | 1

Answered
Error with the division
Use the table2array function to convert the contents of the table to an array. Assign the arrays to new variables rather than o...

24 hours ago | 0

Answered
error [empty sym] using dsolve "Warning: unable to find symbolic solution"
It is likely not possible to derive a closed-form (analytic or symbolic) solution for those. Create an anonymous function to us...

1 day ago | 0

Answered
How to define values in a vector as NaN ?
Try this (using ismember) — A = [1 2 3; 4 5 6]; B = [2 3; 5 6]; C = ismember(A,B) A(C) = NaN .

1 day ago | 1

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Answered
Define an additional variable in ODE solver
This is all a bit confusing, since the differential equations are not them selves functions of ‘C1’ and ‘C2’, so a differential ...

1 day ago | 0

Answered
Can't Uninstall, What Should I Do?
Option #1: Contact Support The uninstall function deletes registry entries as well, however a fresh install should over-write...

1 day ago | 0

Answered
symbolic variables into double array, observability matrix
The variable values need to be provided in order to use the Control System Toolbox funcitons. To do this symbolically, create...

1 day ago | 0

Answered
How can I estimate the parameter of reaction kinetics using ODE solver?
I am not absolutely certain how to approach this because chemical engineering is not an area of my expertise. First, I would ...

2 days ago | 0

Answered
Question in continuous time signals
Everything in a computer are discrete, not continuous (except the voltages on the chips themselves and the outputs of a soundcar...

2 days ago | 0

Answered
How to solve the implicit equation
First, a multiplication operator (my best guess, anyway) is missing: ((alfa*Vt*Vmpp*(2*Impp-Isc))/((Vmpp*Isc+Voc*(Impp-Isc))*(...

2 days ago | 0

Answered
How can we combine the two figures?
‘When you execute the code below, two plots are drawn.’ No, not without knowing what the variables are. However the prob...

2 days ago | 0

Answered
Calculate this matrix in a more general and shorter way
Yes, actually. However since it appears that the objective is to do a Fourier transform, I would set it up a bit differently ...

2 days ago | 0

Answered
ODE45/ODE15 inquiry about nonlinear spring
Since the system appears to describe a differential-algebraic equation, see the documentation section on Solve Differential Alge...

2 days ago | 0

Answered
Symbiological output using 'syms' and 'pretty' commands
Experiment with the indexing into the expressions (since this is a straightforward solution to a number of otherwise difficult p...

2 days ago | 0

Answered
How do I reflex a plot?
Try this — u = -8:1:1.3; v = -pi:pi/10:pi; for k = 1:numel(v) x{k,1} = 1 + u + exp(u)*cos(v(k)); y{k,1} = v(k) +...

3 days ago | 0

Answered
how to increase function values through its derivetive
Do some simple experiments to see what produces the desired result — syms k x dx1 = 2*x; ...

3 days ago | 0

Answered
Problem to solve integration
Change this — f = @x sin(x); to this — f = @(x) sin(x); That should work. .

3 days ago | 0

Answered
Removing a particular legend from plot
The first two lines have the same line style. To see them individually, choose a different line style for each. To label t...

3 days ago | 0

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Answered
how to solve the following equation?
Try this — a=[1,2,3]; afcn = @(b) ((b-2).*(b+1))./((b+3).*(b-1)); [estb,fval] = fminsearch(@(b) norm(afcn(b) - a), rand) ...

3 days ago | 0

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Answered
How to plot 3D filled contour ?
It would help to know the data and the desired result. One option is to use the surf function and contour3 — [X,Y,Z] = peak...

3 days ago | 0

Answered
Using ode45 for a non linear differential equation with a term in a vector form
I do not understand the problem. Is the objective to estimate a parameters of the differential equation from data? The tim...

3 days ago | 0

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Answered
why do I get an error "First input argument must be a function handle"
I have no idea what the code does. See if this paproximates the desired result — nUn = 2000; nU2n = 1500; nU3n = 200;...

4 days ago | 1

Answered
I need help solving RC circuit using Leplace inverse, then graph the output which is in the symsum form
Sometimes a bit fo force (such as using vpa) is necessary — syms s t Ys2(s)=((2*s^2+7*s+3)/(2*s^3+11*s^2+15*s+4)*(2*s+2)/(...

4 days ago | 1

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Answered
2D contour plot with given matrix
Two possibilities — M = [25, 25, 25 111.5, 137.8, 245.1 146.3, 178.3, 296.4 111.5, 137.8, 245.1 25, 25, 25]; figure ...

4 days ago | 0

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Answered
from curve fit to look up table
The question is a bit ambiguous. Interpolation of some sort would appear to be the best option, and of course the approach de...

4 days ago | 0

Answered
Curve fitting for multivariable
There are several options. I’m using fminsearch here. xdata = ... [0.882263937 0.882263937 0.882263937 0.882263937 0...

4 days ago | 0

| accepted

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