### Step 4: Calculating a Time Course

In the tree on the left under Tasks you can find the entry called Time Course. Selecting this entry in the tree will bring you to the time course settings dialog.

(Click here to go to the Time Course dialog)
Here you can set all parameters for calculating a time course like starting time, end time, how many data points are to be stored and, last but not least, the method for calculating the trajectory. So far you can choose between deterministic simulation or stochastic simulation. Depending on the simulation method, you have some more parameters that can be changed in the table toward the bottom of the dialog, but the default values should suffice most of the time.

Once all values are set, the run button can be used to excecute the timecourse calculation. To see the results for the calculation, the Time Course node in the tree on the left has a subnode called Result, it contains a table with the calculated values for all variables (This only works if the Save Result in Memory checkbox is checked). The Result window also has a button that allows saving the results to a file.

Sometimes the results of a calculation are to large to be stored in memory, or you might want to have other items in the result that are not in the Result table. For those cases, COPASI provides means to specify so called reports in which the user can specify the items that are to be written to a file.

The easiest way to create a report is to choose one of the predefined report with COPASI's Output Assistant which can be started by clicking the button with the same name at the bottom of the screen.

The dialog features a large number of predefined reports as well as plots. Each item on the right side of the dialog, when selected, provides a description on the left side of the dialog. By clicking the `Create!` button, when a item has been selected, the corresponding plot or report is created.

If the item that has been created was a plot, everything is set and next time, the corresponding task is run, a plot window should appear that shows the selected plot.

If the selected item however was a report, you have to choose a file to which the report will write its contents. This can be done by clicking on the `Report` button at the bottom of the Time Course window. The dialog that pops up lets you choose the report which you want to associate with a file (since a task can have more than one report) and it lets you specify a filename.

Once you are done, just click the `Confirm` button and next time you run the task, a file with the contents of the report will be written to disk.