Evolve / Step Backward   ()

Summary

Evolves the frontmost simulation backward one time step.

Description

When you select this command, the frontmost simulation will evolve backward one time step.

While AstroGrav is calculating the next state of the system, the Evolve / Stop command is available for you stop the evolution, and the Evolve / Settings... command is available for you to change the time step. In many simulations though, the calculations will be completed in a fraction of a second, and you will not notice this.

The time that it takes AstroGrav to evolve the system through one time step is extremely variable, but depends mainly on the following factors.

• The fewer objects there are in a simulation, the less time it will take to evolve. If there are only a few objects in a simulation, it may evolve through one time step in a tiny fraction of a second, whereas if there are thousands of objects in a simulation, it may take many seconds to evolve through one time step.

• The greater the proportion of objects whose mass is below the mass threshold (specified with the Evolve / Settings... command), the less time it will take to evolve. If a simulation has a significant proportion of objects that have low masses, increasing the mass threshold may significantly reduce the time it takes to evolve, without significantly reducing the accuracy.

• The shorter the time step is, the less time it will take to evolve. Reducing the time step can significantly reduce the time it takes to evolve, but this is not always the case - if the time step is already small, reducing it will have little effect on the evolution time.

• The faster your computer is, the less time it will take to evolve.

See Also:

• Evolve / Settings...()that sets the evolver settings of the frontmost simulation.

• Evolve / Stop()that stops the evolution of the frontmost simulation.

• Edit / Undo()that undoes the latest change to the frontmost simulation.

• Edit / Redo()that redoes the most recently undone change to the frontmost simulation.

• Window / New Ephemeris...()that generates an ephemeris for each selected object in the frontmost simulation, while it is evolving.

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