# how to plot the equation

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shiv gaur on 21 Feb 2022
Commented: Image Analyst on 21 Feb 2022
x(0)=1;
y(0)=0
t=1:15;
for n=1:15
x(n+1)=(x(n-1)-y(n))/n+1;
y(n+1)=(x(n)+y(n)-t)/n+1
plot(t,x)
end
##### 2 CommentsShowHide 1 older comment
Image Analyst on 21 Feb 2022
Yeah, I figured that, but what I meant by my answer below is you're supposed to do
x(1) = 1;
y(1) = 0;

Image Analyst on 21 Feb 2022
Edited: Image Analyst on 21 Feb 2022
Indexing starts at 1, not 0. Also, check your formulas - they look weird.
For example in
y(n+1)=(x(n)+y(n)-t)/n+1
you need t(n), not just t which is the entire array.
y(n+1)=(x(n)+y(n)-t(n))/n+1
Image Analyst on 21 Feb 2022
OK, so it's all working now that you're starting your vectors at index 1 instead of 0, and changed t to t(n)? If so, can you accept this answer because I pointed out the problems? If not, post your current code so we can continue to work on it. This is what I got. Let me know if it's the same as what you have.
x = zeros(1, 16);
y = zeros(1, 16);
x(1)=1;
% y(1)=0
t=1:15;
for n = 2: length(x) - 1
fprintf('n = %d.\n', n);
x(n+1) = (x(n-1)-y(n)) / n + 1; % Note only n is in the denominator, not (n+1)
y(n+1) = (x(n)+y(n)-t(n)) / n + 1;
end
n = 2. n = 3. n = 4. n = 5. n = 6. n = 7. n = 8. n = 9. n = 10. n = 11. n = 12. n = 13. n = 14. n = 15.
plot(t, x(1:end-1), 'b.-', 'LineWidth', 2, 'MarkerSize', 30);
hold on;
plot(t, y(1:end-1), 'r.-', 'LineWidth', 2, 'MarkerSize', 30);
grid on;
xlabel('t', 'FontSize', 20);
ylabel('x or y', 'FontSize', 20);
title('x or y VS. t', 'FontSize', 20);
legend('x', 'y')

R2021b

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