[Weiqiang Liu]

Hi all,

I am trying to use macros F_C0 and F_C1 to obtain cell indexes of a specific face. I read user manual of UDF and found the following statement:
"F_C1 returns the cell index for c1 if it exists"

if the face I am handling is a boundary face, then c1 would be undefined. I am wondering what F_C1 will return if c1 is not defined.

I need to use c1 cell index in my UDF code. If c1 is not defined, then will F_C1 return a void or a cell index?

Best regards

Weiqiang