I do not know how to fix this problem (code below)

%ode45_ex.m

%This program solves a system of 3 differential equations

%by using ode45 function 

%y1'=y2*y3*t, y2'=-y1*y3, y3'=-0.51*y1*y2
%y1(0)=0, y2(0)=1.0, y3(0)=1.0

clear; 

clc;

initial=[0.0 1.0 1.0]

tspan=0.0:0.1:10.0;

options=odeset('RelTol', 1.0e-6, 'AbsTol', [1.0e-6 1.0e-6 1.0e-6]);

[t, Y]=ode45(@dydt3, tspan, initial, options);

P=[t Y];

disp(P);

t1=P(:,1);

y1=P(:,2);

y2=P(:,3);

y3=P(:,4);

fid=fopen('output.txt','w');

fprintf(fid,'        t      y(1)         y(2)         y(3)   \n');

fprintf(fid, '------------------------------\n');

for i=1:2:101

fprintf(fid, '  %6.2f    %10.2f   %10.2f    %10.2  \n' t1(i), y1(i), y2(i), y3(i));  %HERE

end

fclose(fid);

plot(t1, Y(:,1), t1, Y(:,2), '-.', t1, Y(:,3), '--'), 
xlabel('t'), ylabel('Y(1), Y(2), Y(3)')
title('Y vs. t');
grid

text(6.0, -1.2, 'y(1)')

text(7.7, -0.25, 'y(2)')

text(4.2, 0.85, 'y(3)');

The program keeps saying that something is wrong with the t1. I bolded where it says the problem is.

Thanks for your help

[Steven Lord]

Please copy and paste the full text of the error message you receive (all the red text) into a comment. Don't paraphrase, post it exactly as it appears in the Command Window.

Answer 1

[Aquatris]

You are missing a comma (,) before the t1 there. You are also missing a comma at line "plot(t1,.." before the "title".

Also in the code you provide, you do not give "@dydt3" function any further mistakes cannot be found.