Hi
The MathCad worksheet and ODE that Werner helped me solve is attached to my previous post see http://communities.ptc.com/message/236394#236394 so if you need test your answer download the file attached in that link.
What I am now trying to do solve, by way of this new post, is to find the depth of water in the tank for a particular / prescribed outflow. To do this I made the ODE variable function and then tried to pass back the particular value to the ODE solver in order to find the depth of water for a particular user prescribed outflow (POF). I have done this previously with an ODE and to my surprise it worked. This time however it seems to want to work but then results in the see jpeg error attached. The ODE is more complicated than my previous one because the function is nested but it would be interesting to see if it can be done by the brains trust.
Kind regards, Mark