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Modulus calculation to find decreasing YearQuarter 
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#1
Nov1412, 11:52 AM

P: 21

I am feeling silly because I can't seem to crack this, but maybe I have been starring at it too long. I am trying to find a math function that will yield a single unit decrement of the currently defined Year/Quarter. This is a software UI thing: I am trying to create a script to decrement, in single steps, the current Year/Quarter shown. The issue is that it needs to wrap around back to the start. Hence I was trying to use a Modulus operator.
Here's what I need, decrementing the current quarter: Q1 > Q4 (of the prior year) Q2 > Q1 Q3 > Q2 Q4 > Q3 I can get three of the four conditions via mod(), but I can't seem to work out one calculation that works for all. Adding another number somewhere is fine; I am really just trying to do this without having to also include an IF() statement to look for the Q1>Q4 condition. It doesn't have to deal with the "Q" string part; I already am splitting the string up and just handling the numeric portion separately. I then rebuild the string. Same with the year; that is handled in a separate step as well. I just need to calculate the quarter number, and I am trying to save 1 line of code. :) And if anyone cares, this is being done in FileMaker 12 scripting language. Has most of the modern conveniences, but not quite as flexible as most real fullblown languages. This is what I have currently (yields 3 correct results; slightly modified from actual code to make it more readable): Here is my working version for incrementing (modified again; Yearwrap around IS done with an IF statement, but not the Qrtr number): Thanks Justin 


#2
Nov1412, 09:55 PM

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The usual trick is to add the base first to make sure it doesn't go negative: Mod(val+41; 4)



#3
Nov1512, 09:41 AM

P: 21

It seems like it wouldn't quite work in this situation; I could still end up with a zero result of the mod(); I want a result from 1 through 4. Val = 1 ; Mod (1 + 4  1 ; 4 ) = Mod (4) = 0. And if I add 4 to that, it works for that one, but not the others. I have thought of doing a subtraction ( 4  Mod(...) ) but that just inverts the order of results, yielding f(3) = 1. But it does work for f(1).



#4
Nov1512, 03:27 PM

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Modulus calculation to find decreasing YearQuarter
1+Mod(4*n1+xn; 4) 


#5
Nov1512, 05:04 PM

P: 21

Yeah, I didn't explicitly mention it but my sample data showed it.
Thanks for this function. I will assume that 'x' in your formula is the starting quarter number. n = 1 all the time, in my case. So that essentially reduces the formula to: 1+Mod(x+2 ; 4 ) When I work through it in my head it works! Now to test it... :) Thanks! 


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