How to....

after i have played a game against the computer i like to have it give me the basic analysis of my game.... i really love this feature and is one of the main reasons i plan on upgrading my account.

anyways...as the computer is analyzing the game a white/black bar is displayed below the board indicating "strength" --- this is my question... how do "I" learn how to do this calculation myself - is there a formula? what is this "strengh" based on 

An advantage of 1 is equal to a pawn. In high level chess, players fight for advantages worth less than a pawn (such as having the bishop pair or a space advantage). The computer measures these advantages in "centipawns" (1/100 of a pawn). There are rules of thumb you can use to get an estimate, but you can not calculate it without a computer. Some examples I know that you can use to get an estimate are:

Pawn = 1

Knight = 3

Bishop = 3

Rook = 5

Queen = 9

Possession of Bishop Pair = .5

1 Tempo = .3

Rook on the 7th = 6

Both Rooks on the 7th = 13

A pawn on the 7th = 5

Rook Pawns = .85

A passed pawn on the 6th = 3

Active King in the Endgame = +4

Minor Pieces in the Endgame = 2.5

Rook in the Endgame = 5.5

A bishop would be worth slightly more than a knight overall, though some unique situations favor a knight such as blockading.  Bishops defend weak squares (or gaps in pawn structures) and due to their range their power rises in an endgame.  

thank you 

but whats with the "need" for a computer to do the calculation - surely there is a formula (heck the computer itself is using this "equation" to do its own math... why cant i do the same?

see i run a group dedicated to the promotion of Tri-Dimensional Chess so im hoping to use this "formula" to calculate the same values for Tri-Dimesnional Chess, which i seriously believe is the NEXT chapter in the grand history of chess