OAK's Formula | Optimize command applies expression simplification to the formula in the active cell. If it finds that the formula can be expressed more simply, it offers the option to replace the original formula with the simplified one.
OAK is equipped with about fifty algebraic rules which it uses for transformations such as these.
If none of these rules matches any portion of the formula in the active cell, OAK will say so.
Tip: OAK can perform as valuable as service in not offering an optimization for a formula, as in delivering one. For example, OAK would not offer any change to IF(A1+B2+C3+D5>E6+F7+G8+H9,A1+B2+C3+D4,E6+F7+G8+H9), though it looks as if it should; the first and third expressions are not quite the same. Is it is mistake? Who knows. But it is certainly a candidate for careful checking.
Wrinkles
Some simplifying actions can be performed on formulas completely safely; that is, the simplified formula will always give the same answer as the original formula. For example, =A1++B1 can be rewritten as =A1+B1, and depended on to give the same answer.
But some transformations are not so safe. They will give the same answer most of the time, but not always. This point is explained further at What's safe in simplification.
OAK therefore divides the rules for algebraic transformation between
| • | ones that are Conservative, that is, can be applied in any circumstances without any danger of changing the meaning of a formula, |
| • | ones that are Aggressive, that is, need to be applied carefully, because there are circumstances in which they might change the meaning of a formula. |
Although OAK invites you to confirm that you would like it to make any formula changes that it proposes, there is no facility for undoing the change after it is made. Keep a copy of your spreadsheet.