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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...

5 years ago | 0

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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 .

5 years 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 ...

5 years ago | 0

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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...

5 years ago | 0

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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...

5 years ago | 0

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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...

5 years ago | 0

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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))*(...

5 years ago | 0

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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...

5 years ago | 0

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

5 years ago | 0

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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...

5 years ago | 0

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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) +...

5 years ago | 0

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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; ...

5 years ago | 0

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

5 years ago | 0

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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...

5 years 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) ...

5 years 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...

5 years ago | 0

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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...

5 years ago | 0

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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;...

5 years ago | 1

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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)/(...

5 years 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 ...

5 years 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...

5 years ago | 0

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

5 years ago | 0

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Answered
Change x axis increments
See Axes Properties, specifically XScale, YScale, ZScale. .

5 years ago | 0

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How can I make a single letter or specific letters bold without using the latex interpreter for title, axis, and labels?
Se the Interpreter property in the text documentation. The default interpreter is 'tex', and it is possible to use it with any ...

5 years ago | 1

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Answered
How can I add conditions to a system of equations?
Use the assume function — syms q w e r t y u i o real assume([q w e r t y u i o]>=1 & [q w e r t y u i o]<=9) eqn1= (w*r)/...

5 years ago | 0

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Plot fitting curve (x,y) in 3D (x,y,z)
One option is the waterfall plot. I would start with it. . .

5 years ago | 0

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Answered
Mesh Plot surface dimensions must agree
The easiest solution in that instance is either to reverse the first two arguments to surf or transpose the ‘Z’ matrix. .

5 years ago | 1

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Calculating gradient of f in point A?
Create them as functions — syms x1 x2 f = x1 + x2^2; A = [5, 6]; f_grad_diff(x1,x2) = [diff(f, x1), diff(f, x2)]; f_grad...

5 years ago | 0

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Answered
How do i find the ZCR of a speech signal?
The easiest way is to use the zerocrossrate function in the Signal Processing Toolbox (however that likely amounts to cheating)....

5 years ago | 0

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How to perform global sensitivity analysis on a set of data
This is new to me. The only reference I was able to find (other than the SimBiology functions) is this GitHub link Global sensi...

5 years ago | 2

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