Excel arrays

Hey every1...pls help me out.. I want to knw how to enter date array in any formula of excel..plssss help asap..

More detail required.

actually I m tryin to use mduration formula in which settlement date and maturity date is required. I have to calculate mduration of many entries which are arranged in a row according to maturity date. I can see that thr is option for entering array in the date field of the formula but not getting how to enter the array so tht calculation is faster..

Pls reply anybody....I am badly confused..Can mdauration be used for arrays????