Calculate number of days between two posting dates

Hi Experts,

I need to develop a report which gives number of days of a material in each storage location. Or based on movement type for eg if a material has movement type 101, then i need that posting date and when the same material has movement type 311 i need that posting date and find the number of days between the two posting dates.

In my first level DSO i already have posting date material and movement type fields. How do i calculate the number of days. If i have a cube above it with a field 'Lead time' then this field should have th number of days populating through a routine.

Can someone please help me with the routine.

Regards,

Kshama.