Numbering weeks for the years of this century. An easy problem?

*To*: mathgroup at smc.vnet.net*Subject*: [mg89027] Numbering weeks for the years of this century. An easy problem?*From*: Guillermo Sanchez <guillermo.sanchez at hotmail.com>*Date*: Sat, 24 May 2008 03:52:30 -0400 (EDT)

According to ISO 8601:2004(E), parr. 2.2.10 the a calendar week number is defined as ordinal number which identifies a calendar week within its calendar year according to the rule that the first calendar week of a year is that one which includes the first Thursday of that year and that the last calendar week of a calendar year is the week immediately preceding the first calendar week of the next calendar year. Could any body build a function for numbering the week for the years this century? A think it is not an easy problem (for instance teh solution given by Excel sometime is wrong A solution for period 2000-2027 is also wellcome. In this period the 53-week years are 2004, 2009, 2015, 2020, 2026; Guillermo