Question: Adding an Extra Real Number Term to ODE Produces Complex Number Solution

Hi everyone,

I'm a beginner in maple and coding in general.

I'm making a model that need to solve a set of linear ODE in maple. Say I have model 1 and model 2.

In model 1, everything works fine and the results I get match with the experiments. However, when I modify model 1 into model 2 by adding 1 additional term multiplied by sigma (a constant) in the set of the ODE, The equations solved by maple produced complex number instead. 

May I know the reason why maple produces complex number as the result?

Please find attached the worksheet. SP1JH1B1.mw

The set of ODE are at the "longitudinal behaviour" section and the ODEs are deq2..6. When I set sigma=0 (basically back to model 1), maple gives me real number solutions again.

If I don't put "evalf" in front of value(dsolve(...)) (see sol_L), Maple produces `[Length of output exceeds limit of 1000000]`

Any help would be greatly appreciated.

Thanks in advance!