Add a default yearfrac (Excel.Actual360)

Author: Eric Forgy

src/excel.jl

@@ -43,6 +43,7 @@ function DayCounts.yearfrac(startdate::Date, enddate::Date, dc::Thirty360)
     end
     return DayCounts.thirty360(y2-y1,m2-m1,d2-d1)
 end
+DayCounts.yearfrac(startdate::Date, enddate::Date) = DayCounts.yearfrac(startdate::Date, enddate::Date, Thirty360())
 
 """
     Excel.ActualActual()