Error using plot Vectors must be the same length.

Question

Hazel Can 2022-5-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1726170-error-using-plot-vectors-must-be-the-same-length

评论： Torsten 2022-5-24

采纳的回答： David Hill

在 MATLAB Online 中打开

Error using plot

Vectors must be the same length.

Error in midpointfinal (line 33)

plot(t,y_m,'-o')

clc; clear all;
h=0.01;
Tmax = 2; % Maximum time
Tmin=1;    %Minimum time
n = (Tmax-Tmin)/ h;  % Maximum number of steps
%n=(t(2)-t(1))/h;
t = linspace(0,1,n+1);;
alpha=0.5;
mu=20;
%initials%
y_m(1)=2;
y_m(2)=exp(20.*h)+cos(h);
f_m(1)=20.*(y_m(1)-cos(t(1)))-sin(t(1));
f_m(2)=20.*(y_m(2)-cos(t(2)))-sin(t(2));
% Analytical solution of the differential equation
exact = @(t) exp(mu*t)+cos(t);
plot(t,exact(t));
hold 
%Numerical solution
%f= @(t,y) mu*(y-cos(t))-sin(t); % Governing system of equations
%Midpoint Two step method%
for i=3:n
    y_m(i)=y_m(i-2)+2.*h.*f_m(i-1);
    f_m(i)=20.*(y_m(i)-cos(t(i)))-sin(t(i));
end
plot(t,exact(t))
hold
plot(t,y_m,'-o')
legend('Exact Solution','Leapfrog Solution','Location','NorthEast')
xlabel('t')
ylabel('y')

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Atsushi Ueno 2022-5-24

在 MATLAB Online 中打开

Vector t and y_m must be the same length.

h = 0.01;
n = 100;  % Maximum number of steps
t = linspace(0,1,n+1);
y_m(1)=2;
y_m(2)=exp(20.*h)+cos(h);
f_m(1)=20.*(y_m(1)-cos(t(1)))-sin(t(1));
f_m(2)=20.*(y_m(2)-cos(t(2)))-sin(t(2));
for i=3:n
    y_m(i)=y_m(i-2)+2.*h.*f_m(i-1);
    f_m(i)=20.*(y_m(i)-cos(t(i)))-sin(t(i));
end
size(t)
ans = 1×2
     1   101
size(y_m)
ans = 1×2
     1   100