Array indices must be positive integers or logical values Error

2018 11 4
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更新时间：2018 11 4
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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

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madhan ravi
madhan ravi 2018-11-4
编辑：madhan ravi 2018-11-4

0 个投票

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)

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madhan ravi
madhan ravi 2018-11-4
编辑：madhan ravi 2018-11-4
Note : some of your parameters are not defined , I suspect you don't need loop for your case
Emma Powderly
Emma Powderly 2018-11-4
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);
Emma Powderly
Emma Powderly 2018-11-4
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
madhan ravi 2018-11-4
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
Emma Powderly 2018-11-4
thanks I was following a flowchart and confused the for for the if loop I get it now thank you

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