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ode45 or dsolve

Asked by felik kamwera on 24 Jun 2019 at 6:24
Latest activity Commented on by felik kamwera on 24 Jun 2019 at 7:15
whats wrong with my code.. its from a book but cant run
tspan=[0 4];
y0=[0.02;0];
[t,y]=ode45('unforced1',tspan,y0);
plot(t,y(:,1));
grid on
xlabel(time)
ylabel(Displacement)
title(Displacement Vs Time)
hold on;
its function is function yp = unforced1(t,y)
yp = [y(2);(-((c/m)*y(2))-((k/m)*y(1)))];

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felik kamwera on 24 Jun 2019 at 6:37
okay m=5,, k=1000,c=1000, can u help how the code should look like
What are c and m defined in your function ? Have you assigned any values to them ?
felik kamwera on 24 Jun 2019 at 6:47
should i give them values in the function definition or call?

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1 Answer

Answer by madhan ravi
on 24 Jun 2019 at 6:57
 Accepted Answer

tspan=[0 4];
y0=[0.02;0];
m=5;
k=1000;
c=1000;
[t,y]=ode45(@(t,y)unforced1(t,y,c,m,k),tspan,y0); % function call
plot(t,y(:,1));
grid on
xlabel('time')
ylabel('Displacement')
title('Displacement Vs Time')
%function definition
function yp = unforced1(t,y,c,m,k) % if your version is prior to 2016b save this in a separate file name unforced1.m
yp = [y(2);
(-((c/m)*y(2))-((k/m)*y(1)))];
end

  1 Comment

felik kamwera on 24 Jun 2019 at 7:15
thank u very much...i have seen where i was wrong..again thank u

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