System of 2 second order coupled differential equations with Mathcad

[kevin75019]

Hello,

Using Mathcad to solve a system of 2 second order coupled differential equations, I issue a problem with the "D" function (used to solve a diffrentiel equation) when there is more than 1 parameter inside.

Here is the system :

I convert this system to have only first order equations :

Then, I can't find other way than making a D matrix with my parameters :

Then, I issue my problem : its seems that mathcad refuse to have a D function with more than 1 parameter :

So, if anybody here can find a way to solve this system, please let me know !

Regards

Kevin

 

[excognito]

You need to define your system of equations in a different way. The standard method is to create a single state vector from all of the DEs.

You can also incorporate the parameters A, B and K into the DE, setting their derivatives to be 0.

Read the Help on rkfixed for further information.

 

[PNachtwey]

I don't think the D array can be a two dimensional array. Here is an example controlling the level of a second tank of a two tank system
Scroll down to get to the D array. There is a lot of extra stuff.

http://www.deltamotion.com/peter/Mathcad/TwoTanks/Mathcad - t0p2 p pi Alin's two tanks Cascade.pdf

Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com