Beantwortet
How to Extract Delayed State Terms in a Model with Distributed Delay?
So in the distributed case you want to extract y2_delayed(t) = integral_{tau = t-1.5]^{tau = t-0.5} y2(tau) dtau thus the te...

3 Monate vor | 0

| akzeptiert

Beantwortet
Solution of a 2nd order non linear implicit differential equation using ode15i implicit solver
% Initial conditions y0 = [0 2]; % initial displacement and velocity %yp0_guess = [0; 0]; % Initial guess for derivatives %...

3 Monate vor | 0

Beantwortet
Different behaviour when using symbolic simplification on norm() for scalars and vectors?
If you want to define the norm of the difference of two real-valued n-dimensional vectors, use norm_x_minus_y = sqrt(sum((x-y)....

3 Monate vor | 1

| akzeptiert

Beantwortet
Unable to perform assignment because value of type 'optim.problemdef.OptimizationExpression' is not convertible to 'double'.
If you use optimvars on the right-hand side of the assignment hapsCoreAvailability(coreIdx) = T_start + execTime; (T_start is ...

3 Monate vor | 0

Beantwortet
Estimation the parameters of a non-linear equation
If only reproducing the x-P curve matters, you can use the following code. If the density of the x-values in certain regions sh...

3 Monate vor | 0

Beantwortet
Find the combination that maximize the objective function values from the data set.
filename = 'Objective Optimization MATLAB.xlsx'; data = xlsread(filename); data(:,7:end) = []; n = 1; while(size(data,1) > 0...

3 Monate vor | 0

| akzeptiert

Beantwortet
Source code for solving second order ODE/PDE using PINN
Why do you want to use code for partial differential equations if you have an ordinary differential equation to solve ? syms ps...

3 Monate vor | 0

Beantwortet
To RESHAPE number of elements must not change
It means that the number of elements in the original and the reshaped array must be the same: a = rand(15,1); a_ok = reshape(a...

3 Monate vor | 0

Beantwortet
how to modify code for distributed delay
r = 1.5; fun = @(t,x)[r*x(1)*(1-x(2));x(1)]; x0 = [0.5;0]; tspan = [0 20]; [t,x] = ode45(fun,tspan,x0); plot(t,x(:,1)) gri...

3 Monate vor | 1

| akzeptiert

Beantwortet
Finding the closest coordinate from a surface plot based on a X, Y location
lat_GMM and lon_GMM are not within the rectangle in which data for z are supplied. In this case, interp2 returns NaN because i...

3 Monate vor | 0

Beantwortet
Global stability of an epidemiology
clear; clc; % Define the parameters of the epidemic model alpha1 = 0.0444; % transmission rate alpha3 = 0.2; % fixed rec...

3 Monate vor | 0

| akzeptiert

Beantwortet
How to fit kinetic model to estimate kinetic parameter from experimental data
I replaced C = b(11)-(0.9*y(2))-(0.947*y(3))-(0.9*y(4)/0.511)-(1.137*(y(1)-1.04)); by C = b(1)-(0.9*y(2))-(0.947*y(3))-(0.9*y...

3 Monate vor | 1

Beantwortet
I am trying to solve the system of coupled partial differential equations described in the attachment using the function pdepe. My code runs into this error:
"pdepe" is a solver for parabolic-elliptic partial differential equations (with a second-order spatial derivative term modelling...

3 Monate vor | 1

| akzeptiert

Beantwortet
How to input a novel boundary condition for a coupled PDE system
xOde = [0 1].'; % Define coupling points for ODE definition function [pl, ql, pr, qr] = PDE_PSw_EK_BC_2(xl, yl, xr, yr, t, v...

3 Monate vor | 0

| akzeptiert

Beantwortet
quadprog output: this problem is non-convex
Maybe there are Inf or NaN coefficients in your A ? The following small example works. A = rand(53,66); [m,n] = size(A); opti...

3 Monate vor | 0

Beantwortet
Problem with finding the global minimum with fmincon
What are x(1) - x(4) in your mathematical description ? In other words: What are your optimization parameters ? You don't defin...

3 Monate vor | 0

Beantwortet
Why do my laptop and work computer produce different results when adding a small term to a matrix?
In the representation with 4 decimal places, the results don't seem to differ. But it's not unusual that computations on diffe...

3 Monate vor | 0

| akzeptiert

Beantwortet
When i call and run this code it just save the Phase1 results in CSvV file not other results .
Use PhaseTable = struct2table(PhaseResults); writetable(PhaseTable,'Phase.csv'); instead of % Write Phase re...

3 Monate vor | 0

Beantwortet
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...

4 Monate vor | 0

| akzeptiert

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

4 Monate vor | 0

Beantwortet
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...

4 Monate vor | 0

Beantwortet
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 ...

4 Monate vor | 0

| akzeptiert

Beantwortet
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...

4 Monate vor | 1

| akzeptiert

Beantwortet
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 ...

4 Monate vor | 0

Beantwortet
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, ...

4 Monate vor | 1

| akzeptiert

Beantwortet
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 ...

4 Monate vor | 0

Beantwortet
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)

4 Monate vor | 0

| akzeptiert

Beantwortet
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);

4 Monate vor | 2

Beantwortet
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...

4 Monate vor | 0

Beantwortet
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)

4 Monate vor | 0

| akzeptiert