How to Smoothly Distribute Monthly Data Values Across Daily Intervals?

[josse34]

Hi!
I have a problem to resolve this question :

I have a total value each month :
January = 60
Fébruary = 80
March = 130
April = 150
May = 180
June = 200
July = 210
August = 170
September = 140
October = 90
November = 60
December = 50

I want to calculate the value each day of year, but the total of this values each month must be exactly like value previously describing.
Also, the graphic render must be with smoothing line, like spline or simpson rule.

See attached a excel base http://cjoint.com/?CKilaalz7z2

How to make this ?!

Thank you so much and have a nice day!

Bye

 

[SteamKing]

Simpson's rule is for numerical integration, so you don't want that.

 

[josse34]

Any method is ok for me, the simply is the best because i must integrate this into PHP code after!
Do you any idea?
Thanks