VLS is computed by the FAC. GD, s anf F come from the FMGS for the data entered into the MCDU on initialisation. This is wht GD doesn't change (computed as 2 x GW + 80 + 1 Knt/1000' above 20,000') but VLS will.
To fing the FAC computed GW, go to MCDU menu, then AIDS, the Aplha Param Call Up. The GW computed by the 2 FACS should be on page 1, although this may vary with your company's configuration.