Weekends exclusion in SAP BW

Hi,

We have a requirement to calculate the difference between 2 dates.

The weekends should not be included, they must be excluded in the calculation.

We have the FM RKE_SELECT_FACTDAYS_FOR_PERIOD to calculate the difference between dates excluding the weekends based on factory calendar. But unfortunately this FM is not available in the SAP BW system.

Please let me know if there is any such FM available in the SAP BW system.

Thanks.