Answered
"Empty sym" when solving a system of linear equations with different conditions
Your system only has a (nontrivial) solution if i = 1. In this case, the solution is given as below. syms Z1A Z2A Z3A Z4A Z1B Z...

2 years ago | 0

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Answered
Temperature profile in a pipe flow with Matlab pdepe solver
I corrected as much as I could, but the computation of Q looks different in your code in comparison to the article. %% Main cod...

2 years ago | 0

Answered
Substitute partial differential into symfun
syms G(h) h(t) t Q = G(h) dGdt = diff(Q,t) % -> D(G)(h(t)) occurs s = children(dGdt) % Now define G(h) and derive: G ...

2 years ago | 1

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Answered
Using a loop to add rows to a struct, but the counter overwrites the rows.
I don't know how "trial" and "blockInfo" are organized. Here is one suggestion: for ifile = 1:3 for s = 1:nTrials struc...

2 years ago | 0

Answered
I am trying to perform a simple operation FOR loop. I think I am not able to get the indexing right.
%% why does not the following operation work Because the numbers 1,2 and 3 in t1, t2 and t3 are not indices you can loop over, ...

2 years ago | 0

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Answered
Kelvin functions ker kei functions evaluation
The value kei(0) = -pi/4 only exists in the limit : syms x a = exp(pi*1i/4); limit(imag(besselk(0,a*x)),x,0,"right") limit(i...

2 years ago | 0

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constrained optimization with Matlab, symbolic function
If your function f is symbolic, you first have to convert it to a numerical function by using "matlabFunction". k_tot = ...; a...

2 years ago | 0

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I am unable to find the minimum value of function f in this optimization problem. The solver always returns 0 for all variables which is not possible. I am unable to correct.
The solution is correct: A*x <= b is satisfied, and since all elements in the f-vector are positive, 0 is optimal. Maybe you wa...

2 years ago | 0

Answered
int function is not working properly in matlab
Evaluate gamma(n_star_D3(i)+l_d+1) gamma(n_star_D3(i)-l_d) and you will see the reason. Consequently, Gff_D3(i)...

2 years ago | 0

Answered
Negative sign produced by "functionalDerivative" - why?
As you can see here at the bottom of the page https://uk.mathworks.com/help/symbolic/sym.functionalderivative.html functionalD...

2 years ago | 0

Answered
fmincon get the wrong answer
Cost of buy with price 26 is 2*26 + c = 152 in your setting. Note that although you don't generate energy, Cg_i(0,a,b,c) = c - t...

2 years ago | 1

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Answered
Why the results of three codes with the same expression and method are different ?
Integrate equation (1) from x = 0 to x = x, and the problem will become much easier. dvdx0ini = 1; St = [0.1,0.5,1]; hold on ...

2 years ago | 0

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Curve fitting and parameter estimation with lsqcurvefit
% Load data data = readtable('infections.csv'); dates = datetime(data.Date, 'InputFormat', 'dd-MMM-yy'); cases = data.Cases; ...

2 years ago | 0

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How to set lower bound lb as a function of optimization variable.
Use function "nonlcon" to define nonlinear equality and inequality constraints. If v(i) depends linearly on the solution variab...

2 years ago | 2

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When using 'quadprog' how do I limit certain solutions so that they can only become whole numbers?
https://uk.mathworks.com/matlabcentral/answers/660423-can-i-solve-mixed-integer-quadratic-programming-miqp-problems-in-matlab-us...

2 years ago | 0

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Synthax for equation in script
r0 = 3; r1 = 4; delta = linspace(-r0,r0,31).'; k = linspace(-r1,r1,31).'; 0.5*sqrt((delta+k.^2).^2+4*k.^2)

2 years ago | 0

Answered
Equal arc discretization method code
warning("off") syms t t1 t2 % Parameters R2 = 12; %outer radius (between this radius and R1 is constant arc increment) b = 2...

2 years ago | 0

Answered
A quatity is being solved by a self consistent integration
format long syms x A = 2000; a = 500; b = 1000; Z = 0; for i=1:20 f = x^4*((A^2+Z^2)/(A^2+4*(x^2+a^2)))^4 / (sqrt(x^2+...

2 years ago | 0

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Answered
How can I write the term \sum_{q=1}^{m} b_{pq}(t)g_q(y_q(t-\tau_{q}(t))) to produce the same graph
I don't know exactly what you are asking for, but if it's about solving Equation 1, you will have to use a solver for delay diff...

2 years ago | 0

Answered
Non linear fitting with 3 independent variables
M = load("Data.mat"); fun = @(A,B,C,E)(A - B*M.IL - C*M.a).*exp(-E*M.Vf); f = @(A,B,C,E) fun(A,B,C,E) - M.K; A0 = 13.5*13.2; ...

2 years ago | 2

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Finite Difference Method - Central Difference Method for Groundwater Flow Problem
It would help if you included the mathematical description of your problem in order to compare with your coding (equation(s) to ...

2 years ago | 0

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Answered
How to return a vector output when a vector input is given to a function_handle representing a constant function?
This works in both cases: % Usual Case syms x; syms t; u = symfun(x^2,x); u_x = diff(u,x); u_x = matlabFunction(u_x); u_...

2 years ago | 0

Answered
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
Only a single number can be saved in an array element. But you try to save a vector ([a b(i) c 0 0 0 0 0 d(i)]) in a single e...

2 years ago | 0

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Answered
Runge Kutta 4th Order Method for an Equation
Write a function function dy = f(t,y) that accepts t and a vector y of length 2*n with y = [c_1;...;c_n,cbar_1;...;cbar_n] ...

2 years ago | 1

Answered
How can I calculate the integral of Legendre function P(n,theta) ?
The Legendre function is a numerical, not a symbolic function in MATLAB. Further, it's define for -1 < x < 1. So integration f...

2 years ago | 1

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Answered
Plotting discrete Klein - Gordon equation (DKG) with friction in DNA
acceleration(1) = acceleration(numBases) = 0 for every value of i in your loop. From the equation initialVelocities = initia...

2 years ago | 0

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Answered
Trying to solve system of PDE by spacial discretization. Errors are coming frequent . what am i doing wrong ?
Technically, your code works now. But you get NaN values for some dydt's. The reason might be that you start with a complete 0 v...

2 years ago | 0

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Answered
I need help with an error I get
Define F before you call "funcao_forca". It's not set in your code. Maybe you mean F = funcao_forca(t,f); because f is a give...

2 years ago | 1

Answered
Error in untitled22>solveHeatEquation1D (line 32) U(N+2,n+1) = beta(t); Error in untitled22 (line 11) [t, x, U] = solveHeatEquation1D(T, a, b,mu, u0,alpha, N, M);
a = 0; b = 1; % spatial interval T = 0.4; % end time mu = 0.5; % conductivity alpha = 1; ...

2 years ago | 0

Answered
Why does the code always return "-ve" values?
When I run the main, it returns me all negative values though I have given only two negative values. Why not ? The objective is...

2 years ago | 0