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Confusion, matlab, ode45 variables.

by Smiles302
Tags: confusion, matlab, ode45, variables
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Apr22-11, 03:35 PM
P: 26
1. The problem statement, all variables and given/known data

I am very confused over how matlab knows which variables are changeable variables in ode45.

2. Relevant equations // 3. The attempt at a solution

My input is p

Earlier have defined;
a = 1;
k = 1;
w = 1/3;

Then I want to figure out adot and adoubledot from these.

adot = (a)*(p - k/a)^(-1/2);

adoubledot = (a/2)*(p + 3*w*p);

Suddenly realised that I have no idea why matlab would let "a" change but not let "p" and "k" change...

Is there a way to tell matlab that one of the variables is changing in time and the others aren't?
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Apr23-11, 07:19 AM
P: 26
Nobody? =( Does my question make sense?
Apr23-11, 12:57 PM
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jhae2.718's Avatar
P: 1,159
I'm not sure exactly what you're asking. For ode45 you need to define a function. Ode45 uses the function definition for variables. (I think you need to have only one variable For ode45, so if you have more than one you can use a column vector.)

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