Confusion, matlab, ode45 variables.

[Smiles302]

Homework Statement

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

Homework Equations

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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 realized 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?

 

[Smiles302]

Nobody? =( Does my question make sense?

 

[jhae2.718]

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.)