Talk:E-book comb.as

Those diffs are pretty revealing ay? ;-)

• TR → TL - uses TX
• TR → BR - uses TY
• BR → BL - uses TX

Notice that the differences can all be expressed as simple changes of sign of an item in some of the expressions. Tx is -1 or +1, TY is -1, 0 or +1. TX and TY use those values so that they can be used as multipliers to either change the sign of what they multiplied with (if its -1) or leave it unchanged if its +1.