YEARFRAC & Leap Years

  • It looks like a pretty silly problem but it's driving me mad.

    The yearfrac function takes a two dates and a basis. Now assume basis = 1 ( Act / Act ) and two cases:

    1) 06-Jan-06 -> 06-Jan-08 ( 730 days ) = 1.998175182 =>> divisor = 730/1.998175182 = 365.33333

    2) 06-Jan-05 -> 06-Jan-07 ( 730 days ) = 2 =>> divisor = 730/2 = 365

    In case 1) 2008 is a leap year ( but the "leap" has yet to come! ). Can anyone explain me the logic behind? I suppose the extra day is divided by 3 but where is the "Actuality" of the divisor?


  • Re: Yearfrac Calculation


    I don't think the fact that


    the "leap" has yet to come!

    matters. Your range in case 1) covers 3 different years, 1 of which is a leap year therefore the average days per year = 365.33333. This I think


    is the "Actuality" of the divisor



  • Re: Yearfrac Calculation

    I'm not even sure it is really valid to use dates in two years, although they are allowed. The Help page only gives an example to get the fraction that a period is of a year, to give a pro-rata benefit.

  • Re: Yearfrac Calculation

    yearfrac - Fraction of year between dates
    YearFraction = yearfrac(StartDate, EndDate, Basis)

    Not sure about leapyear, it has always been a pain I reCall and something jiuk avoids. I have given the systax so You can check Your spot on just in case

    jiuk[hr]*[/hr] Auto Merged Post;[dl]*[/dl]Also see ----

    YearFraction = yearfrac(StartDate, EndDate, Basis) returns a fraction based on the number of days between dates StartDate and EndDate using the given day-count basis. If EndDate is earlier than StartDate, Fraction is negative.

    YearFraction = yearfrac('14 mar 01', '14 sep 01', 0)

    YearFraction =


    YearFraction = yearfrac('14 mar 01', '14 sep 01', 1)

    YearFraction =


    See Also

    days360, days365, daysact, daysdif, months, wrkdydif, year, yeardays

    NOTE __ Credit to the author of this information jiuk has nabbed it, be happy to edit the post on evidence of Your work, sorry buddy I cant remember its old stuff I have saved <shrug> As always full credit where due

  • Re: YEARFRAC &amp; Leap Years

    Thanks guys!

    it's probably true that 'Yearfrac' work just for period below/equal to one year. What is misleading is that it works for all date constellations for all method but Act/Act.


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