Mathematical Formula - Financial Calendar

Actual Day Basis

ΔDYS = f(DT2) – f(DT1)

where:

f(DT) = 365 (yyyy) + 31 (mm – 1) + dd + INTG (z/4) – x
and
for mm ≤ 2
   x = 0
   z = (yyyy) – 1
for mm > 2
   x = INTG (0.4mm + 2.3)
   z = (yyyy)
INTG = Integer portion.

Note: Additional tests are performed in order to ensure that the century (but not millennium) years are not considered leap years.

30/360 Day Basis

DAYS = f(DT2) – f(DT1)

where:

f(DT) = 360 (yyyy) + 30mm + z
for f(DT1)
   if dd1 = 31 then z = 30
   if dd1 ≠ 31 then z = dd1
for f(DT2)
   if dd2 = 31 and dd1 = 30 or 31 then z = 30
   if dd2 = 31 and dd1 < 30 then z = dd2
   if dd2 < 31 then z = dd2