For starters Excel has no "lines" it has rows. Assuming your date is in
Column A1:A10 and the x values are in B1:B10 and the y values are in C1:C10,
then in D1 put the formula =IF(MONTH(A1)=2, B1+C1,"") and drag the formula
down through D10

Tyro

wrote in message
...
Can anyone tell me what formula i could use to perform a function
whenever for example,the month of April or perhaps the 31 days of a
specific month appears in the data.


For example,below is 3 columns and if you imagine that the time column
extends to
a full year.
Time x values Y values
15/02/2008 17:15 1590158.49 9.12
15/02/2008 17:30 1590168.64 10.15
15/02/2008 17:45 1590178.3 9.66
15/02/2008 18:00 1590187.91 9.61
15/02/2008 18:15 1590197.4 9.49
What i want to do is if the first column contains the month of feb
then add the corresponding x and y values
IE taking the first line, the first column does represent a day in
Feb
so add 1590158.49 and 9.12 which will produce 1590167.61

I would be most grateful for any help.
Thanks
David