How to run ode45 for various parameter depending on the output of the solver

I have written a code to solve 8 coupled ordinary differential equations using ode45. I am solving for positions(x,y) of a particle in 2D coordinates.I also a have a gradient value matrix of two variable parameters which are changing depending on the positions of the particle transport. Those values are simulated to another software and exported to matlab as a matrix. My problem is how can I change the parameter values depending on the output I got from ode45 and calculate positions? I can calculate and run the code for constant parameter which is not changing depending on the positions but what can i do if i want to change them?

Any help would be highly appreciated?

Answer 1

[Walter Roberson]

http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

[regenerate arif]

I do not know the function of parameter. I only know those gradient values at different grid (x,y) points.