As far as I know you cannot yet create calculated fields in schedules using the API.
If you already know the parameters that need to be calculated you could pre-build a minimal schedule manually in the template consisting of only the parameters and calculated fields required then use the API to duplicate it and add/remove/hide other fields and apply filters as required.
You could even make a 'SuperSchedule' packed full of parameters and many combinations of calculated fields, then duplicate and customise it on the fly as needed.
Hopefully access to calculated fields is available in the next release.
Access a broad range of knowledge to help get the most out of your products and services.