Array indices must be positive integers or logical values Error

I'm trying to execute this for loop and I keep coming up with same error. I don't understand why this is happening so if you could help at all it would be greatly appreciated.

for t= linspace(0,99)

C_1=x0;

C_2=x0_dot+(Wn*x0);

x(t)= (C_1 + (C_2*t))*exp(-Wn*t);

end

Answer 1

[madhan ravi]

t= linspace(0,99);
for i = 1:numel(t)
C_1=x0;
C_2=x0_dot+(Wn*x0);
x(i)= (C_1 + (C_2*t(i)))*exp(-Wn*t(i));
end
plot(t,x)

if x0, x0_dot and Wn are scalars meaning a single number then you can do something like:

t = linspace(0,99);
C_1=x0;
C_2=x0_dot+(Wn*x0);
x = (C_1 + (C_2.*t)).*exp(-Wn.*t);
plot(t,x)

[madhan ravi]

Note : some of your parameters are not defined , I suspect you don't need loop for your case

[Emma Powderly]

Thank you but I get a new error on both options about the multiplication.

Error using * Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To perform elementwise multiplication, use '.*'.

Error in Lab2 (line 23) x = (C_1 + (C_2.*t))*exp(-Wn.*t);

[madhan ravi]

just put .* instead of *

[Emma Powderly]

Thanks if you don't mind me asking why doesn't the first option work when x0,x0_dot and Wn are scalars?

[madhan ravi]

actually the first option works but its useless to use a loop if you can do it directly why go around if you can take a shortcut?

[Emma Powderly]

thanks I was following a flowchart and confused the for for the if loop I get it now thank you

[madhan ravi]

Anytime :)