MATLAB Answers

For Loop Help Needed

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Kevin Egan
Kevin Egan on 19 Mar 2020
clear all, close all, clc
figpath = '../figures/';
%% generate Data
polyorder = 5;
usesine = 0;
sigma = 10; % Lorenz's parameters (chaotic)
beta = 8/3;
rho = 28;
n = 3;
x0=[-8; 7; 27];
range2 = [((10^3.6)*.001), ((10^3.7)*.001) , ((10^3.8)*.001) , ((10^3.9)*.001) , ((10^4)*.001)]
for i = range2
N = length(tspan);
options = odeset('RelTol',1e-12,'AbsTol',1e-12*ones(1,n));
[t,x]=ode45(@(t,x) lorenz(t,x,sigma,beta,rho),tspan,x0,options);
for j=1:length(x)
dx(j,:) = lorenz(0,x(j,:),sigma,beta,rho);
dx_n0 = (dx);
Theta_n0 = poolData(x,n,polyorder,usesine);
m = size(Theta_n0,2);
total_n0(i,:) = [dx_n0 Theta_n0];
I currently have the above code but am receiving the error "Index in position 1 is invalid. Array indices must be positive integers or logical values.". Is it possible to run this code through the range of values and save each resulting dataframe separately?


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Kevin Egan
Kevin Egan on 19 Mar 2020
function dy = lorenz(t,y,sigma,beta,rho)
dy = [
From running the code without total_n0(i,:) = [dx_n0 Theta_n0]; there doesn't seem to be an error. It appears that the code runs through the entire range and saves the final (10^4)*0.001 from tspan
Ameer Hamza
Ameer Hamza on 19 Mar 2020
I also don't have function poolData, but from your description in comment, the error seems to be related to dimensions of dx_n0 and Theta_n0.
Kevin Egan
Kevin Egan on 19 Mar 2020
Yes, if I could possibly align the results side by side, that would be ideal. Although the length of the matrix would be unequal.
The resulting total_n0 would initially have 59 columns, therefore I'd like to add the next matrix to the 60th column.

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Answers (1)

Harsha Priya Daggubati
Harsha Priya Daggubati on 23 Mar 2020
It would be more helpful, if you could copy the entire error message you get while posting the question in the forum. I guess the issue might be with the value of 'i'. You can make use of breakpoints to debug the issue much easily.
If that's no the case other workaround would be to possibly define 'total_n0' to be a cell array, to store variable length arrays.
total_n0{i} = [dx_n0 Theta_n0];
Hope this helps!


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