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Calculate the normal vector between two nodes in the space
n = [0 0 1] points from A to B. So I don't understand what you mean by "normal" to the line connecting two points in 3d. Usual...

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Parse error at observed data
% Observed data (replace with actual data) % Format: [time, infected, isolated, treated, recovered] observed_data = [ 0, ...

circa un mese fa | 0

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Multivariate regression for constrained dependent variables
Define a Nx12 matrix A as A = [x11,x12,x13,x14,x15,x16,x21,x22,x23,x24,x25,x26] and a Nx1 vector b as b = ones(N,1) and sol...

circa un mese fa | 0

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Newton's method gives NaN. Can someone improve my code?
Your undamped Newton's method throws you from x = 0.5 to x = 46 appr. in the next step. Here, your function cannot be evaluated ...

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3D integration over a region bounded by some planes.
f = @(x,y,z)x.^2+y+2*z; N = [100,1000,10000,100000,1000000,10000000,100000000]; Fi = zeros(numel(N),1); Fo = Fi; for i = 1:n...

circa un mese fa | 1

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Fitting multiple datasets with unique parameters using lsqcurvefit to a normalized function and constraints between datasets.
If your model functions share common parameters, you must run "lsqcurvefit" on all yi with all parameters present (in your case ...

circa un mese fa | 0

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Error in Model Fitting
% Define the time vector and observed data time = [0, 1, 2, 3, 4, 5]; % Example time points observed_I = [10, 15, 20, 25, 30, ...

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Complex Number Ignition Error: Ray transfer matrix analysis
imag(1./q)*lambda/pi is negative, thus sqrt(imag(1./q)*lambda/pi) is complex. MATLAB does not know how you want it to plot ...

circa un mese fa | 0

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Solving with ode45 with a solution dependant variable in the ode
fun = @(t,y) sum(y)*y; zspan = [0 3e-2]; y0 = [1 2 3 4 5]; [T,Y] = ode45(fun,zspan,y0); plot(T,Y)

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I'm getting a matrix as output when I'm expecting a vector
Maybe you mean I = ones(n+1,1); instead of I = ones(n+1);

circa un mese fa | 2

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multiplying a function handle by a constant
This is Heun's method, but your solution explodes. I get the same results with a MATLAB ODE integrator like ODE45. You will hav...

circa un mese fa | 0

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Problems by calculating zero points of a cubic function
x=0.1:0.1:0.5; p = arrayfun(@(i)roots([-2 1 x(i) -8]),1:numel(x),'UniformOutput',0); p = cell2mat(p)

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I'm getting following error: Array indices must be positive integers or logical values.
Indexing in MATLAB starts with 1, not with 0.

circa un mese fa | 1

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Error imposing space-derivative-dependent boundary condition with solvepde using variable state.uy - Error: Unrecognized field name "uy".
According to the documentation (User's guide, page 2-128), g can be a function of x,y,t and u. The boundary condition of a seco...

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How to build an empiric cdf/pdf of a compound poisson continuos distribution
clear all; close all; clc rng(200724) %mean and standard deviation of a given sample (sample of Yi) mu_c = 4432.62; var_c= 53...

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Invalid expression during a function handle
Must read Kernel = @(x) ... instead of Kernel = @x ...

circa 2 mesi fa | 2

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Help understanding how function handle is used
Somewhere in your code you defined a fitness function which assumes that inputs j and k are integers function fitness = Ft(x,j,...

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Error in for loop: Index exceeds matrix dimensions.
matrix_f=[1 2 3; 1 2 3; 4 5 6; 7 8 9; 7 8 9; 10 11 12]; unique(matrix_f,'stable','rows') Note that this code will remove all d...

circa 2 mesi fa | 1

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Why does this technique not work?
I already gave you the code how to order a vector according to the ordering of "u". Why don't you use it ? Your method is wrong...

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Setting unknown constants in equation for known data
how can i do that ? By solving the system yi - f(xi,a,b,c) = 0 for a,b and c. Here, (xi,yi) are your data points. If f is l...

circa 2 mesi fa | 1

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lsqcurvefit issues due to variables being several orders of magnitude different
load('V1.mat') load('Vp.mat') load('data.mat') V = [V1, Vp]; %voltages a = 1.1792; b = 0.5; e = 1.60217662e-19; Area ...

circa 2 mesi fa | 0

Risposto
X=[.01:.01:1] ; % - example data uniformly going form .01 to 1 in steps of .01 binEdges=[0:0.01:1]; %- the bind edges X(6)>b...

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How can I solve the error "Unable to solve the collocation equations -- a singular Jacobian encountered" in bvp4c?
Your ODE system is linear - thus you can determine its general solution having 7 free parameters. But incorporating of your boun...

circa 2 mesi fa | 0

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How to Graph integrals?
According to proposition 4, the red curve should be the inverse bidding function X and the blue curve should be the inverse bidd...

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how to plot function with 2 variables? using fsolve or bisection ?
Use "fimplicit": https://uk.mathworks.com/help/matlab/ref/fimplicit.html

circa 2 mesi fa | 0

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how to get a good estimate of the positive parameters that will give a good fit of the curves to real data?
You should avoid defining the same data, parameters and variable definitions multiple times in your code (specific_data, gamma, ...

circa 2 mesi fa | 1

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How can I find a unique solution within tolerance using solve?
As long as rank(A) equals 3 in the below code, your system of linear equations has a unique solution. syms Rx Risop Rison V1=2...

circa 2 mesi fa | 1

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function must return a column vector
Allocate dy as a column vector before assigning values to it: %Ordinary differential equation dy = zeros(4,1); dy(1)=alpha*(1...

circa 2 mesi fa | 0

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I'm having trouble solving a system of nonlinear equations with the fmincon function.
Use % Options for fmincon options = optimoptions('fmincon', 'Algorithm', 'interior-point', 'Display', 'off','ConstraintToleran...

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Simulation - number of samples
Is there a preset (optimum) value and how is this determined? As big as necessary and as small as possible. You will have to te...

circa 2 mesi fa | 1

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