TCPI - correct formula?

 Friends,

 In some books it is given as 

TCPI= BAC-EV / BAC-AC

while in some other book it is given as 

TCPI = BAC-EV / EAC-AC

 

Can some point confirm which is the correct formula for TCPI?

 

Both are correct.

 

TCPI= BAC-EV / BAC-AC

It's the efficiency needed to complete within BAC, i.e. on original plan.

 

TCPI= BAC-EV / EAC-AC      is used when a new EAC has been obtained.

It's the efficiency needed to complete within the EAC.

 

You might want to check some numerical problems and confirm that this is the case, i.e. which formula gets used when.

 

Thanks.