"IF requires between 2 and 3 arguments, but was given 1" error

I get lost in all the ) and don't really understand the flow of the logic.

Instead of a nested if approach you might consider a lookup method instead.

For example you could lay out all your rules in a table and look up the Signal by doing something like this:

Formula for index in Table 1:

=B2&(YLS>TL)&(TH>YHS)&(YLS>TC)&(TC>YHS)

Formula for index in Rules table:

=B2&C2&D2&E2&F2

Formula in column I of Table 1 to use the indexes to look up the Signal.

=INDEX(Rules::Signal,MATCH(H2,Rules::Index,0))

SG

I started to look at it but it is way too long and complex. It would be better from a design and debugging point of view to use a collection of columns to do each separate logical test then roll those results into a much shorter and simpler formula. Another advantage of doing it this way is you can ensure each logical test is doing what you expect it to do, not just that the syntax is correct and doesn't throw errors.

I tried to parse it out and it looks like there are multiple instances of IF statements that are of the form IF(AND(....)) which would give the error you are getting. I had to put it into TextEdit to see how all the parentheses aligned. This is what I see:

Several parentheses are out of place. All IF statements have only one parameter.

Long formulas like that generally cause trouble. They are hard to debug.

Very likely you can accomplish the same thing another way.

Could you explain what you are trying to do?

SG