Index exceeds the number of array elements (5)

53 views (last 30 days)
I am solving Forward Euler for dy=x*y+1, x between 0 and 1, y(0)=0 h=.25
I have gotten the error message "Index exceeds the number of array elements (5)" after rearranging the code (because I was getting other error messages). How can I clear it up?
clc; clear all;
h=0.25; % step size
xmin=0;
xmax=1;
x=xmin:h:xmax; %x boundaries
n=length(x);
y=zeros(1,n);% Initial condition
for i=1:n
x0=0;
dy=(x(i+1)*y(i)+1);
x(i+1)=n*h;
y(i+1)=y(i)+h*dy;
end
figure(1)
hold on
plot (y,x,'b', 'linewidth',2)
title ('Forward Euler')
  1 Comment
Matt J
Matt J on 7 Oct 2019
Kolleggerm1's comment moved here:
So I added a line to the for-loop to identify the max of i which seemed to solve the exceeding error, but now I get an error "Array indices must be positive integers or logical values" in line 10
clc; clear all;
h=0.25; % step size
xmin=0;
xmax=1;
x=xmin:h:xmax; %x boundaries
n=length(x);
y=zeros(1,n);% Initial condition
for i=1:n
i=0:1:4;
dy=(x(i+1)*y(i)+1);
x(i+1)=n*h;
y(i+1)=y(i)+h*dy;
end
figure(1)
hold on
plot (y,x,'b', 'linewidth',2)
title ('Forward Euler')

Sign in to comment.

Accepted Answer

the cyclist
the cyclist on 7 Oct 2019
You have initialized x and y to be vectors of length 5. But in your for loop, i reaches the value value 5, and then you try to access x(i+1), which is x(6), which does not exist. You could run your for loop over just i = 1:n-1.
  6 Comments
the cyclist
the cyclist on 17 Mar 2021
I did not fully understand your question.
I think you should open a new one, with your code included.
MATLAB is a procedural language, and always runs through the code in order.
Guanyang Liu
Guanyang Liu on 17 Mar 2021
Thank you so much for your prompt reply! I'll start a new thread then

Sign in to comment.

More Answers (1)

Matt J
Matt J on 7 Oct 2019
for i=1:n-1

Categories

Find more on Creating and Concatenating Matrices in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!