Built-in DatePlus and DateDifference are much slower than DaysPlus

*To*: mathgroup at smc.vnet.net*Subject*: [mg87829] Built-in DatePlus and DateDifference are much slower than DaysPlus*From*: Luci Ellis <luci at verbeia.com>*Date*: Fri, 18 Apr 2008 02:39:39 -0400 (EDT)

Dear MathGroup, I am not sure if this is a question or comment. I thought I should note the following timing differences between the built-in DateDifference and DatePlus functions, and the corresponding functions from the Calendar package, DaysBetween and DaysPlus. Timings are from an original iMac G5. Do[ DaysBetween[{2000, 3, 3}, {2002, 2, 2}];, {1000}]; // Timing Out[49]= {1.08407, Null} Do[ DateDifference[{2000, 3, 3}, {2002, 2, 2}];, {1000}]; // Timing Out[50]= {5.39334, Null} In[56]:= Table[DaysPlus[{2000, 1, 1}, i], {i, 1000}]; // Timing Out[56]= {1.88357, Null} In[57]:= Table[DatePlus[{2000, 1, 1}, i], {i, 1000}]; // Timing Out[57]= {2.75215, Null} I got a 100% speed-up by switching to the functions from the package. This is a puzzle, because the commands from the Calendar package would seem more general. If anyone has any insights on why this might be, that would be interesting. Otherwise I'm just putting the information out there, in case it is helpful to someone. Best regards, Luci