```Date: Dec 9, 2012 2:29 AM
Author: text-dude
Subject: Re: want to save internal data from ode45 - is this true?

On 12/09/2012 08:25 AM, someone wrote:> I want to save internal data from ode45, but NOT from the intermediate> timesteps (only the full timestep).>> I found this:> http://www.mathworks.co.uk/matlabcentral/newsreader/view_thread/246590>> And tried to implement it - but I think it's wrong.>> If the last line(s) of the mass-matrix is zero, the ode45-solver will> not even solve it.>> Am I right? Isn't there any way of only solving the whole (full)> timestep internal values of ode45?This is what I'm referring to:----------dx(1)/dt = f1(t,x(1),x(2))dx(2)/dt = f2(t,x(1),x(2))y = f3(t,x(1),x(2)).Then define a problem of dimension 3,set the mass matrix to[1,0,0; 0,1,0; 0,0,0] (rows are seperated by ;)and the system todx(1) = f1(t,x(1),x(2))dx(2) = f2(t,x(1),x(2))dx(3) = x(3) - f3(t,x(1),x(2))Often it is essential that the initial conditionyou provide for y are consistent, i.e. set exactlyx(3) (t=0) = f3(t=0,x(1)(t=0),x(2)(t=0)).----------I don't think this should work, with zeros in the last row of the mass-matrix. Am I right?
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