Where I can get all the formula information?

[mike99]

In the wikihelp, I can onle find some basic parameters and formula. And I can't find such as roundup(), rounddown(),

[jeffh]

You can try this page at the wikihelp. it covers a lot of the standard formulas you might want to use and gives some examples of syntax.

http://wikihelp.autodesk.com/Revit/enu/Community/Tips_and_Tricks/Families%2c_Parameters%2c_Formulas/Formulas_for_%22Everyday%22_Use

[mike99]

great! it's what I want
thanks a lot