Just a few comments/questions:) First you are not really writing down ranges [x,y] mathematically here, second you haven't provided a definition of <else> for A1/A2/A3 if your condition in your if statement returns false ie. if it falls outside of this range, third is that parameters A1/A2/A3 can test for the same condition and return values accordingly... Perhaps you could elaborate on what you were trying to make here.
As you've written it down (is/-/=), it's something like A1=3" if A=-17", A2=4" if A is a rational number (lenght/number?)/always true?, A3=5" if A=-1.5" 🙂 So I'm going to assume that's not what you meant. ^^ But actually if you want to include 4" and 21" in your specified range [4",21"] = 4"≤A≤21" your formula/conditional statement should look like:
A1 with formula; if(and(not(A < 4"), not(A > 21")), 3", 0")
A2 with formula; if(and(not(A < 21.5"), not(A > 23")), 4", 0")
A3 with formula; if(and(not(A < 23.5"), not(A > 25")), 5", 0")
The formula's posted earlier actually represents the range as (4",21") instead of [4",21"]. Since you haven't specified values for A1/2/3 if A falls outside of these ranges, like barthbradley I've set all of them to 0... But possibly you need it to be something else, that remains unclear...