How can I get the first and last date of a week, based on the week number and the year

[Bruno Baguette <bruno(dot)baguette(at)gmail(dot)com>]

Hello !

I have a week number (ISO 8601) and a year, based on theses values, I 
would like to get the first and the last dates of that week.

How I can do that ?

The only solution is doing a big generate_series to build a subset that 
contains the week of all the dates between the 01/01 || year and the 
31/12 || year. But I find that solution quite dirty and ressources 
consumming.

Is there a cleanest way to do that ?

Many thanks in advance !

Regards,

--
Bruno Baguette - bruno(dot)baguette(at)gmail(dot)com