Counting occurrences of an intermittent event depending on start, end and frequency












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I am sorry if this is a trivial question (I am really bad at math ;-)), but I cannot manage to find a convincing mathematical solution for it.



So, let's suppose events that occur intermittently along the days:



Event A occurs every 2 days, starts on day 1
Event B occurs every 2 days, starts on day 2
Event C occurs every 3 days, starts on day 3
etc.


Visually presented:



days 1 2 3 4 5 6 7 8 ...
A * * * *
B * * * *
C * *


Now, I want to compute how many events of each observer will see, depending on the day they arrive and the day they leave.



Thus, I have the following variables:



event
frequency: 1/2, 1/3...
startingDay: 1, 2, 3...
observer
firstDay: 1, 2, 3...
lastDay: 6, 7, 8...
totalDays = lastDay - firstDay + 1


Is there a formula that could easily compute for each observer how many events of each type he will see? I tried combining rounding (flooring totalDays*frequency) + some modulo, but I cannot seem to find the hang of it.










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    0












    $begingroup$


    I am sorry if this is a trivial question (I am really bad at math ;-)), but I cannot manage to find a convincing mathematical solution for it.



    So, let's suppose events that occur intermittently along the days:



    Event A occurs every 2 days, starts on day 1
    Event B occurs every 2 days, starts on day 2
    Event C occurs every 3 days, starts on day 3
    etc.


    Visually presented:



    days 1 2 3 4 5 6 7 8 ...
    A * * * *
    B * * * *
    C * *


    Now, I want to compute how many events of each observer will see, depending on the day they arrive and the day they leave.



    Thus, I have the following variables:



    event
    frequency: 1/2, 1/3...
    startingDay: 1, 2, 3...
    observer
    firstDay: 1, 2, 3...
    lastDay: 6, 7, 8...
    totalDays = lastDay - firstDay + 1


    Is there a formula that could easily compute for each observer how many events of each type he will see? I tried combining rounding (flooring totalDays*frequency) + some modulo, but I cannot seem to find the hang of it.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      I am sorry if this is a trivial question (I am really bad at math ;-)), but I cannot manage to find a convincing mathematical solution for it.



      So, let's suppose events that occur intermittently along the days:



      Event A occurs every 2 days, starts on day 1
      Event B occurs every 2 days, starts on day 2
      Event C occurs every 3 days, starts on day 3
      etc.


      Visually presented:



      days 1 2 3 4 5 6 7 8 ...
      A * * * *
      B * * * *
      C * *


      Now, I want to compute how many events of each observer will see, depending on the day they arrive and the day they leave.



      Thus, I have the following variables:



      event
      frequency: 1/2, 1/3...
      startingDay: 1, 2, 3...
      observer
      firstDay: 1, 2, 3...
      lastDay: 6, 7, 8...
      totalDays = lastDay - firstDay + 1


      Is there a formula that could easily compute for each observer how many events of each type he will see? I tried combining rounding (flooring totalDays*frequency) + some modulo, but I cannot seem to find the hang of it.










      share|cite|improve this question











      $endgroup$




      I am sorry if this is a trivial question (I am really bad at math ;-)), but I cannot manage to find a convincing mathematical solution for it.



      So, let's suppose events that occur intermittently along the days:



      Event A occurs every 2 days, starts on day 1
      Event B occurs every 2 days, starts on day 2
      Event C occurs every 3 days, starts on day 3
      etc.


      Visually presented:



      days 1 2 3 4 5 6 7 8 ...
      A * * * *
      B * * * *
      C * *


      Now, I want to compute how many events of each observer will see, depending on the day they arrive and the day they leave.



      Thus, I have the following variables:



      event
      frequency: 1/2, 1/3...
      startingDay: 1, 2, 3...
      observer
      firstDay: 1, 2, 3...
      lastDay: 6, 7, 8...
      totalDays = lastDay - firstDay + 1


      Is there a formula that could easily compute for each observer how many events of each type he will see? I tried combining rounding (flooring totalDays*frequency) + some modulo, but I cannot seem to find the hang of it.







      algebra-precalculus






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      edited Dec 7 '18 at 15:44







      Serge B.

















      asked Dec 7 '18 at 15:32









      Serge B.Serge B.

      1013




      1013






















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          $begingroup$

          After decomposing the problem and trying every possible combination for a few days, I think I found the solution. At least, it seems to work for every possible case I can think of. It might be possible to reduce it, but at least, it works.



          numberOfEventsSeen = ceil( (totalDaysOfObservation - ( (eventFrequency - (
          (dayOfArrival - 1 - eventStartingDay - 1) % eventFrequency) )
          % eventFrequency) ) / eventFrequency )


          where



          ceil() = ROUNDUP in Excel for instance
          totalDaysOfObservation = dayOfDeparture - dayOfArrival - 1
          eventFrequency = 2 (if event happens every 2 days), 3, etc.


          (Note: sorry if this is by no means a normal mathematical notation ;-))






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            0












            $begingroup$

            After decomposing the problem and trying every possible combination for a few days, I think I found the solution. At least, it seems to work for every possible case I can think of. It might be possible to reduce it, but at least, it works.



            numberOfEventsSeen = ceil( (totalDaysOfObservation - ( (eventFrequency - (
            (dayOfArrival - 1 - eventStartingDay - 1) % eventFrequency) )
            % eventFrequency) ) / eventFrequency )


            where



            ceil() = ROUNDUP in Excel for instance
            totalDaysOfObservation = dayOfDeparture - dayOfArrival - 1
            eventFrequency = 2 (if event happens every 2 days), 3, etc.


            (Note: sorry if this is by no means a normal mathematical notation ;-))






            share|cite|improve this answer









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              0












              $begingroup$

              After decomposing the problem and trying every possible combination for a few days, I think I found the solution. At least, it seems to work for every possible case I can think of. It might be possible to reduce it, but at least, it works.



              numberOfEventsSeen = ceil( (totalDaysOfObservation - ( (eventFrequency - (
              (dayOfArrival - 1 - eventStartingDay - 1) % eventFrequency) )
              % eventFrequency) ) / eventFrequency )


              where



              ceil() = ROUNDUP in Excel for instance
              totalDaysOfObservation = dayOfDeparture - dayOfArrival - 1
              eventFrequency = 2 (if event happens every 2 days), 3, etc.


              (Note: sorry if this is by no means a normal mathematical notation ;-))






              share|cite|improve this answer









              $endgroup$
















                0












                0








                0





                $begingroup$

                After decomposing the problem and trying every possible combination for a few days, I think I found the solution. At least, it seems to work for every possible case I can think of. It might be possible to reduce it, but at least, it works.



                numberOfEventsSeen = ceil( (totalDaysOfObservation - ( (eventFrequency - (
                (dayOfArrival - 1 - eventStartingDay - 1) % eventFrequency) )
                % eventFrequency) ) / eventFrequency )


                where



                ceil() = ROUNDUP in Excel for instance
                totalDaysOfObservation = dayOfDeparture - dayOfArrival - 1
                eventFrequency = 2 (if event happens every 2 days), 3, etc.


                (Note: sorry if this is by no means a normal mathematical notation ;-))






                share|cite|improve this answer









                $endgroup$



                After decomposing the problem and trying every possible combination for a few days, I think I found the solution. At least, it seems to work for every possible case I can think of. It might be possible to reduce it, but at least, it works.



                numberOfEventsSeen = ceil( (totalDaysOfObservation - ( (eventFrequency - (
                (dayOfArrival - 1 - eventStartingDay - 1) % eventFrequency) )
                % eventFrequency) ) / eventFrequency )


                where



                ceil() = ROUNDUP in Excel for instance
                totalDaysOfObservation = dayOfDeparture - dayOfArrival - 1
                eventFrequency = 2 (if event happens every 2 days), 3, etc.


                (Note: sorry if this is by no means a normal mathematical notation ;-))







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 12 '18 at 10:07









                Serge B.Serge B.

                1013




                1013






























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