How to add variable to ode45 method?
4 views (last 30 days)
Show older comments
I am solving system of two ODEs with ode45 method, and code is working for constant cross section, that means constant radius R:
function f=fun(z,p)
R=2; sig=1; beta=1;
f(1)=-32*beta/(R^4*p(1));
f(2)=(-(2-sig)*8*f(1)/(sig*R)-f(1)*p(2))/p(1);
[zv,pv]=ode45('fun',[1 0],[1; 0])
But I need to implement solution where R=2-z, z is longitudinal coordinate, it is there already in first row of function. I wrote z=0:0.001:1; and R=2-z, like this:
function f=fun(z,p)
z=0:0.001:1;
R=2-z; sig=1; beta=1;
f(1)=-32*beta/(R^4*p(1));
f(2)=(-(2-sig)*8*f(1)/(sig*R)-f(1)*p(2))/p(1);
[zv,pv]=ode45('fun',[1 0],[1; 0])
But I got errors matrix dimensions must agree, what should I do to correct this? On the other side z need to be equal to zv, do I need to call z=0:0.001:1; different?
0 Comments
Accepted Answer
Torsten
on 7 May 2018
The actual longitudinal coordinate z is transferred to your function "fun" by ODE45:
function f=fun( *z*,p)
You cannot reset this value by
z=0:0.001:1;
and I don't see any reason to do so. Thus just delete the line
z=0:0.001:1;
Best wishes
Torsten.
0 Comments
More Answers (0)
See Also
Categories
Find more on Ordinary Differential Equations in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!