Why am I getting this error trying to plot?
1 view (last 30 days)
Show older comments
Kaylene Widdoes
on 18 Feb 2016
Answered: Walter Roberson
on 18 Feb 2016
Here is my code - it will not let me plot. I am trying to plot everything on one graph and cannot do so.
% HW 3 Part 3
% Coarse solution
h1 = .01;
a = 2;
b = 10;
T = a:h1:b;
M = length(T);
ya = 0;
Y1 = zeros(1,M);
Y1(2) = ya;
for j=1:M-1
f = (1/((T(j))^2)) - (20 * (Y1(j))) / (T(j));
fx = (-2/((T(j))^3)) + ( 20 * Y1(j)) / ((T(j))^2);
fy = (-20 / (T(j)));
fxy = (20 / ((T(j))^2));
fyy = 0;
fxx = (6*((T(j))^-4)) - (40 * (Y1(j)) * ((T(j))^(-3)));
d0 = Y1(j);
d1 = f;
d2 = fx + f*fy;
d3 = fxx + fxy*f + (fx+fy*f)*fy + f*(fxy+fyy*f);
Y1(j+1) = d0 + h*d1 + .5*h^2*d2 + h^3*d3/6;
end
% Fine solution
h2 = .001;
a = 2;
b = 10;
T = a:h2:b;
M = length(T);
ya = 0;
Y2 = zeros(1,M);
Y2(2) = ya;
for j=1:M-1
f = (1/((T(j))^2)) - (20 * (Y2(j))) / (T(j));
fx = (-2/((T(j))^3)) + ( 20 * Y2(j)) / ((T(j))^2);
fy = (-20 / (T(j)));
fxy = (20 / ((T(j))^2));
fyy = 0;
fxx = (6*((T(j))^-4)) - (40 * (Y2(j)) * ((T(j))^(-3)));
d0 = Y2(j);
d1 = f;
d2 = fx + f*fy;
d3 = fxx + fxy*f + (fx+fy*f)*fy + f*(fxy+fyy*f);
Y2(j+1) = d0 + h*d1 + .5*h^2*d2 + h^3*d3/6;
end
% Finer solution
h3 = .0001;
a = 2;
b = 10;
T = a:h3:b;
M = length(T);
ya = 0;
Y3 = zeros(1,M);
Y3(2) = ya;
for j=1:M-1
f = (1/((T(j))^2)) - (20 * (Y3(j))) / (T(j));
fx = (-2/((T(j))^3)) + ( 20 * Y3(j)) / ((T(j))^2);
fy = (-20 / (T(j)));
fxy = (20 / ((T(j))^2));
fyy = 0;
fxx = (6*((T(j))^-4)) - (40 * (Y3(j)) * ((T(j))^(-3)));
d0 = Y3(j);
d1 = f;
d2 = fx + f*fy;
d3 = fxx + fxy*f + (fx+fy*f)*fy + f*(fxy+fyy*f);
Y3(j+1) = d0 + h*d1 + .5*h^2*d2 + h^3*d3/6;
end
%Exact solution
t=a:h3:b;
y = (1./(19.*t)) - (524288./(19.*(t.^20)));
plot(t,y,'k',T,Y1,'bo-',T,Y2,'ro-',T,Y3,'go-')
legend('Exact','h=0.01','h=0.001','h=0.0001')
title('The Taylor Method with 3 meshes')
0 Comments
Accepted Answer
Walter Roberson
on 18 Feb 2016
You are using different T values when you construct Y1, Y2, Y3, but you try to use the same T value to plot all three of them. You should have a T1, T2, T3
0 Comments
More Answers (0)
See Also
Categories
Find more on Discrete Data Plots in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!