How to plot function x(2)=-1/2*x(1)+t?

clc;
clear;
close;
x1=3+3/8;
u=8;
teta(1)=0;
%teta(u+2)=0.2;
for i=1:u
    teta(i+1)=i/5;
end 
for j=1:1
    for k=1:u
        %initial_func=[x1,x2];
        [t,x] = ode45(@IJP4,[teta(k):0.0001:teta(k+1)], x1(j));%
        n=length(t);
        %disp(size(x));
        x1(j)=x(n,1)+4*x(n,1);
        hold on
        %view(30,15);
        x(2)=-1/2*x(1)+t;
        hold on
        figure(1)
        subplot(2,1,1);
        plot(t,x(:,2),'color','g','Linewidth',1.2);
        xlabel('\bf t'); ylabel('$$z$$','interpreter','latex','fontsize',16); zlabel('\bf \psi_2');
        grid on
        hold on
        subplot(2,1,2);
        plot(t,x(:,1),'color','g','Linewidth',1.2);
        xlabel('\bf t'); ylabel('$$y$$','interpreter','latex','fontsize',16); zlabel('\bf \psi_3');
        grid on
        hold on
        figure(2)
        plot3(t,x(:,1),x(:,1),'g');
        xlabel('$$t$$','interpreter','latex','fontsize',16)
        %ylabel('\phi_{2}','fontsize',16)
        ylabel('$$z$$','interpreter','latex','fontsize',16)
        zlabel('$$y$$','interpreter','latex','fontsize',16);
        grid on
        hold on
    end
end

Unable to perform assignment because the left and right sides have a different number of elements.

function dx=IJP4(t,x)
dx=zeros(1,1); % создает нулевой вектор-столбец
dx(1)=-3/2*x(1)-6*x(1);
end

Answer 1

[Cris LaPierre]

Did you mean to assign the result of -1/2*x(1)+t; to the second column of x?

x(:,2)=-1/2*x(1)+t;

If so, then the code runs at least. I have no idea if this is what you expect.

clc;
clear;
close;
x1=3+3/8;
u=8;
teta(1)=0;
%teta(u+2)=0.2;
for i=1:u
    teta(i+1)=i/5;
end 
for j=1:1
    for k=1:u
        %initial_func=[x1,x2];
        [t,x] = ode45(@IJP4,[teta(k):0.0001:teta(k+1)], x1(j));%
        n=length(t);
        %disp(size(x));
        x1(j)=x(n,1)+4*x(n,1);
        hold on
        %view(30,15);
        x(:,2)=-1/2*x(1)+t; % Change here to assign output to column 2
        hold on
        figure(1)
        subplot(2,1,1);
        plot(t,x(:,2),'color','g','Linewidth',1.2);
        xlabel('\bf t'); ylabel('$$z$$','interpreter','latex','fontsize',16); zlabel('\bf \psi_2');
        grid on
        hold on
        subplot(2,1,2);
        plot(t,x(:,1),'color','g','Linewidth',1.2);
        xlabel('\bf t'); ylabel('$$y$$','interpreter','latex','fontsize',16); zlabel('\bf \psi_3');
        grid on
        hold on
        figure(2)
        plot3(t,x(:,1),x(:,1),'g');
        xlabel('$$t$$','interpreter','latex','fontsize',16)
        %ylabel('\phi_{2}','fontsize',16)
        ylabel('$$z$$','interpreter','latex','fontsize',16)
        zlabel('$$y$$','interpreter','latex','fontsize',16);
        grid on
        hold on
    end
end

●

function dx=IJP4(t,x)
dx=zeros(1,1); % создает нулевой вектор-столбец
dx(1)=-3/2*x(1)-6*x(1);
end

[Nauryzbay]

Thank you so much. You've been very helpful.