# Confusion, matlab, ode45 variables.

by Smiles302
Tags: confusion, matlab, ode45, variables
 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?
 P: 26 Nobody? =( Does my question make sense?
 PF Patron P: 1,132 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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