<?php
ini_set('date.timezone', 'Europe/Lisbon');
ini_set('intl.default_locale', 'es_ES');
$cal = IntlCalendar::createInstance();
$cal->set(2013, 5 /* June */, 30); // A Sunday
var_dump($cal->getFirstDayOfWeek()); // 2 (Monday)
echo IntlDateFormatter::formatObject($cal, <<<EOD
'local day of week: 'cc'
week of month : 'W'
week of year : 'ww
EOD
), "\n";
$cal->setFirstDayOfWeek(IntlCalendar::DOW_SUNDAY);
echo IntlDateFormatter::formatObject($cal, <<<EOD
'local day of week: 'cc'
week of month : 'W'
week of year : 'ww
EOD
), "\n";
int(2)
local day of week: 7
week of month : 4
week of year : 26
local day of week: 1
week of month : 5
week of year : 27