Data part, gravity

force_gravity 0.0 -10.
force_gravity_time 0.0 0.0 0.5 1.0 1.e20 1.0

The gravity components as specified in force_gravity are $0$ in x-directions, and $-10. \frac{m}{s^2}$ in y-direction. The force_gravity_time specifies at time versus factor diagram; this is the factor with which the gravity is applied. It should be read as follows: at time $0.0$ the factor is $0.0$, at time $0.5$ the factor is $1.0$ and up to time $1.e20$ the factor remains $1.0$. Later in this tutorial, we will further discuss this topic; so just go straight ahead with reading the next input.

Please realize that all input in Tochnog does not have a specific dimension. The user just should take care that he/she uses consistent units for the different input data, but otherwise the units of input data is not pre-defined.