I am trying to use POSTSAT.f subroutine , I need to evaluate the Y-plus for all cells. Cheers

I remember once trying to write a code to calculate y+ using POSDAT, it did'nt work. You need to run a Do loop over all the boundary cells using, DO IB=1,NBP23 and for some reason POSDAT did'nt recognise this part of the coding.

If you dont get any better response from someone else I suggest you use some other subroutine to do the calculation and store the result in a common block. Notice that most subroutines are called per cell basis. Include some kind of condition so that your calculation is done only once per iteration. Following is an example of coding I use. IC is the cell next to the boundary. Make sure you include all the common blocks required.

DO 20, IB=1,NBP23

IC=LX(IB)/7

INDX=MOD(LX(IB),7)

IREG=IRN(IB)

Hope this helps