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<?php

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4 foldmethod=marker: */

// {{{ Header

/**

 * Calculates, manipulates and retrieves dates

 *

 * It does not rely on 32-bit system time stamps, so it works dates

 * before 1970 and after 2038.

 *

 * PHP versions 4 and 5

 *

 * LICENSE:

 *

 * Copyright (c) 1999-2006 Monte Ohrt, Pierre-Alain Joye, Daniel Convissor

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted under the terms of the BSD License.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 *

 * @category   Date and Time

 * @package    Date

 * @author     Monte Ohrt <monte@ispi.net>

 * @author     Pierre-Alain Joye <pajoye@php.net>

 * @author     Daniel Convissor <danielc@php.net>

 * @copyright  1999-2006 Monte Ohrt, Pierre-Alain Joye, Daniel Convissor

 * @license    http://www.opensource.org/licenses/bsd-license.php

 *             BSD License

 * @version    CVS: $Id: Calc.php,v 1.35 2006/11/21 23:01:13 firman Exp $

 * @link       http://pear.php.net/package/Date

 * @since      File available since Release 1.2

 */

// }}}

if (!defined('DATE_CALC_BEGIN_WEEKDAY')) {

    /**

     * Defines what day starts the week

     *

     * Monday (1) is the international standard.

     * Redefine this to 0 if you want weeks to begin on Sunday.

     */

    define('DATE_CALC_BEGIN_WEEKDAY', 1);

}

if (!defined('DATE_CALC_FORMAT')) {

    /**

     * The default value for each method's $format parameter

     *

     * The default is '%Y%m%d'.  To override this default, define

     * this constant before including Calc.php.

     *

     * @since Constant available since Release 1.4.4

     */

    define('DATE_CALC_FORMAT', '%Y%m%d');

}

// {{{ Class: Date_Calc

/**

 * Calculates, manipulates and retrieves dates

 *

 * It does not rely on 32-bit system time stamps, so it works dates

 * before 1970 and after 2038.

 *

 * @author     Monte Ohrt <monte@ispi.net>

 * @author     Daniel Convissor <danielc@php.net>

 * @copyright  1999-2006 Monte Ohrt, Pierre-Alain Joye, Daniel Convissor

 * @license    http://www.opensource.org/licenses/bsd-license.php

 *             BSD License

 * @version    Release: 1.4.7

 * @link       http://pear.php.net/package/Date

 * @since      Class available since Release 1.2

 */

class Date_Calc

{

    // {{{ dateFormat()

    /**

     * Formats the date in the given format, much like strfmt()

     *

     * This function is used to alleviate the problem with 32-bit numbers for

     * dates pre 1970 or post 2038, as strfmt() has on most systems.

     * Most of the formatting options are compatible.

     *

     * Formatting options:

     * <pre>

     * %a   abbreviated weekday name (Sun, Mon, Tue)

     * %A   full weekday name (Sunday, Monday, Tuesday)

     * %b   abbreviated month name (Jan, Feb, Mar)

     * %B   full month name (January, February, March)

     * %d   day of month (range 00 to 31)

     * %e   day of month, single digit (range 0 to 31)

     * %E   number of days since unspecified epoch (integer)

     *        (%E is useful for passing a date in a URL as

     *        an integer value. Then simply use

     *        daysToDate() to convert back to a date.)

     * %j   day of year (range 001 to 366)

     * %m   month as decimal number (range 1 to 12)

     * %n   newline character (\n)

     * %t   tab character (\t)

     * %w   weekday as decimal (0 = Sunday)

     * %U   week number of current year, first sunday as first week

     * %y   year as decimal (range 00 to 99)

     * %Y   year as decimal including century (range 0000 to 9999)

     * %%   literal '%'

     * </pre>

     *

     * @param int    $day     the day of the month

     * @param int    $month   the month

     * @param int    $year    the year.  Use the complete year instead of the

     *                         abbreviated version.  E.g. use 2005, not 05.

     *                         Do not add leading 0's for years prior to 1000.

     * @param string $format  the format string

     *

     * @return string  the date in the desired format

     *

     * @access public

     * @static

     */

    function dateFormat($day, $month, $year, $format)

    {

        if (!Date_Calc::isValidDate($day, $month, $year)) {

            $year  = Date_Calc::dateNow('%Y');

            $month = Date_Calc::dateNow('%m');

            $day   = Date_Calc::dateNow('%d');

        }

        $output = '';

        for ($strpos = 0; $strpos < strlen($format); $strpos++) {

            $char = substr($format, $strpos, 1);

            if ($char == '%') {

                $nextchar = substr($format, $strpos + 1, 1);

                switch($nextchar) {

                    case 'a':

                        $output .= Date_Calc::getWeekdayAbbrname($day, $month, $year);

                        break;

                    case 'A':

                        $output .= Date_Calc::getWeekdayFullname($day, $month, $year);

                        break;

                    case 'b':

                        $output .= Date_Calc::getMonthAbbrname($month);

                        break;

                    case 'B':

                        $output .= Date_Calc::getMonthFullname($month);

                        break;

                    case 'd':

                        $output .= sprintf('%02d', $day);

                        break;

                    case 'e':

                        $output .= $day;

                        break;

                    case 'E':

                        $output .= Date_Calc::dateToDays($day, $month, $year);

                        break;

                    case 'j':

                        $output .= Date_Calc::julianDate($day, $month, $year);

                        break;

                    case 'm':

                        $output .= sprintf('%02d', $month);

                        break;

                    case 'n':

                        $output .= "\n";

                        break;

                    case 't':

                        $output .= "\t";

                        break;

                    case 'w':

                        $output .= Date_Calc::dayOfWeek($day, $month, $year);

                        break;

                    case 'U':

                        $output .= Date_Calc::weekOfYear($day, $month, $year);

                        break;

                    case 'y':

                        $output .= substr($year, 2, 2);

                        break;

                    case 'Y':

                        $output .= $year;

                        break;

                    case '%':

                        $output .= '%';

                        break;

                    default:

                        $output .= $char.$nextchar;

                }

                $strpos++;

            } else {

                $output .= $char;

            }

        }

        return $output;

    }

    // }}}

    // {{{ defaultCentury()

    /**

     * Turns a two digit year into a four digit year

     *

     * From '51 to '99 is in the 1900's, otherwise it's in the 2000's.

     *

     * @param int    $year    the 2 digit year

     *

     * @return string  the 4 digit year

     *

     * @access public

     * @static

     */

    function defaultCentury($year)

    {

        if (strlen($year) == 1) {

            $year = '0' . $year;

        }

        if ($year > 50) {

            return '19' . $year;

        } else {

            return '20' . $year;

        }

    }

    // }}}

    // {{{ dateToDays()

    /**

     * Converts a date to number of days since a distant unspecified epoch

     *

     * @param int    $day     the day of the month

     * @param int    $month   the month

     * @param int    $year    the year.  Use the complete year instead of the

     *                         abbreviated version.  E.g. use 2005, not 05.

     *                         Do not add leading 0's for years prior to 1000.

     *

     * @return integer  the number of days since the Date_Calc epoch

     *

     * @access public

     * @static

     */

    function dateToDays($day, $month, $year)

    {

        $century = (int)substr($year, 0, 2);

        $year = (int)substr($year, 2, 2);

        if ($month > 2) {

            $month -= 3;

        } else {

            $month += 9;

            if ($year) {

                $year--;

            } else {

                $year = 99;

                $century --;

            }

        }

        return (floor((146097 * $century) / 4 ) +

                floor((1461 * $year) / 4 ) +

                floor((153 * $month + 2) / 5 ) +

                $day + 1721119);

    }

    // }}}

    // {{{ daysToDate()

    /**

     * Converts number of days to a distant unspecified epoch

     *

     * @param int    $days    the number of days since the Date_Calc epoch

     * @param string $format  the string indicating how to format the output

     *

     * @return string  the date in the desired format

     *

     * @access public

     * @static

     */

    function daysToDate($days, $format = DATE_CALC_FORMAT)

    {

        $days   -= 1721119;

        $century = floor((4 * $days - 1) / 146097);

        $days    = floor(4 * $days - 1 - 146097 * $century);

        $day     = floor($days / 4);

        $year    = floor((4 * $day +  3) / 1461);

        $day     = floor(4 * $day +  3 - 1461 * $year);

        $day     = floor(($day +  4) / 4);

        $month   = floor((5 * $day - 3) / 153);

        $day     = floor(5 * $day - 3 - 153 * $month);

        $day     = floor(($day +  5) /  5);

        if ($month < 10) {

            $month +=3;

        } else {

            $month -=9;

            if ($year++ == 99) {

                $year = 0;

                $century++;

            }

        }

        $century = sprintf('%02d', $century);

        $year    = sprintf('%02d', $year);

        return Date_Calc::dateFormat($day, $month, $century . $year, $format);

    }

    // }}}

    // {{{ gregorianToISO()

    /**

     * Converts from Gregorian Year-Month-Day to ISO Year-WeekNumber-WeekDay

     *

     * Uses ISO 8601 definitions.  Algorithm by Rick McCarty, 1999 at

     * http://personal.ecu.edu/mccartyr/ISOwdALG.txt .

     * Transcribed to PHP by Jesus M. Castagnetto.

     *

     * @param int    $day     the day of the month

     * @param int    $month   the month

     * @param int    $year    the year.  Use the complete year instead of the

     *                         abbreviated version.  E.g. use 2005, not 05.

     *                         Do not add leading 0's for years prior to 1000.

     *

     * @return string  the date in ISO Year-WeekNumber-WeekDay format

     *

     * @access public

     * @static

     */

    function gregorianToISO($day, $month, $year)

    {

        $mnth = array (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334);

        $y_isleap = Date_Calc::isLeapYear($year);

        $y_1_isleap = Date_Calc::isLeapYear($year - 1);

        $day_of_year_number = $day + $mnth[$month - 1];

        if ($y_isleap && $month > 2) {

            $day_of_year_number++;

        }

        // find Jan 1 weekday (monday = 1, sunday = 7)

        $yy = ($year - 1) % 100;

        $c = ($year - 1) - $yy;

        $g = $yy + intval($yy / 4);

        $jan1_weekday = 1 + intval((((($c / 100) % 4) * 5) + $g) % 7);

        // weekday for year-month-day

        $h = $day_of_year_number + ($jan1_weekday - 1);

        $weekday = 1 + intval(($h - 1) % 7);

        // find if Y M D falls in YearNumber Y-1, WeekNumber 52 or

        if ($day_of_year_number <= (8 - $jan1_weekday) && $jan1_weekday > 4){

            $yearnumber = $year - 1;

            if ($jan1_weekday == 5 || ($jan1_weekday == 6 && $y_1_isleap)) {

                $weeknumber = 53;

            } else {

                $weeknumber = 52;

            }

        } else {

            $yearnumber = $year;

        }

        // find if Y M D falls in YearNumber Y+1, WeekNumber 1

        if ($yearnumber == $year) {

            if ($y_isleap) {

                $i = 366;

            } else {

                $i = 365;

            }

            if (($i - $day_of_year_number) < (4 - $weekday)) {

                $yearnumber++;

                $weeknumber = 1;

            }

        }

        // find if Y M D falls in YearNumber Y, WeekNumber 1 through 53

        if ($yearnumber == $year) {

            $j = $day_of_year_number + (7 - $weekday) + ($jan1_weekday - 1);

            $weeknumber = intval($j / 7);

            if ($jan1_weekday > 4) {

                $weeknumber--;

            }

        }

        // put it all together

        if ($weeknumber < 10) {

            $weeknumber = '0'.$weeknumber;

        }

        return $yearnumber . '-' . $weeknumber . '-' . $weekday;

    }

    // }}}

    // {{{ dateSeason()

    /**

     * Determines julian date of the given season

     *

     * Adapted from previous work in Java by James Mark Hamilton.

     *

     * @param string $season  the season to get the date for: VERNALEQUINOX,

     *                         SUMMERSOLSTICE, AUTUMNALEQUINOX,

     *                         or WINTERSOLSTICE

     * @param string $year    the year in four digit format.  Must be between

     *                         -1000BC and 3000AD.

     *

     * @return float  the julian date the season starts on

     *

     * @author James Mark Hamilton <mhamilton@qwest.net>

     * @author Robert Butler <rob@maxwellcreek.org>

     * @access public

     * @static

     */

    function dateSeason($season, $year = 0)

    {

        if ($year == '') {

            $year = Date_Calc::dateNow('%Y');

        }

        if (($year >= -1000) && ($year <= 1000)) {

            $y = $year / 1000.0;

            switch ($season) {

                case 'VERNALEQUINOX':

                    $juliandate = (((((((-0.00071 * $y) - 0.00111) * $y) + 0.06134) * $y) + 365242.1374) * $y) + 1721139.29189;

                    break;

                case 'SUMMERSOLSTICE':

                    $juliandate = (((((((0.00025 * $y) + 0.00907) * $y) - 0.05323) * $y) + 365241.72562) * $y) + 1721233.25401;

                    break;

                case 'AUTUMNALEQUINOX':

                    $juliandate = (((((((0.00074 * $y) - 0.00297) * $y) - 0.11677) * $y) + 365242.49558) * $y) + 1721325.70455;

                    break;

                case 'WINTERSOLSTICE':

                default:

                    $juliandate = (((((((-0.00006 * $y) - 0.00933) * $y) - 0.00769) * $y) + 365242.88257) * $y) + 1721414.39987;

            }

        } elseif (($year > 1000) && ($year <= 3000)) {

            $y = ($year - 2000) / 1000;

            switch ($season) {

                case 'VERNALEQUINOX':

                    $juliandate = (((((((-0.00057 * $y) - 0.00411) * $y) + 0.05169) * $y) + 365242.37404) * $y) + 2451623.80984;

                    break;

                case 'SUMMERSOLSTICE':

                    $juliandate = (((((((-0.0003 * $y) + 0.00888) * $y) + 0.00325) * $y) + 365241.62603) * $y) + 2451716.56767;

                    break;

                case 'AUTUMNALEQUINOX':

                    $juliandate = (((((((0.00078 * $y) + 0.00337) * $y) - 0.11575) * $y) + 365242.01767) * $y) + 2451810.21715;

                    break;

                case 'WINTERSOLSTICE':

                default:

                    $juliandate = (((((((0.00032 * $y) - 0.00823) * $y) - 0.06223) * $y) + 365242.74049) * $y) + 2451900.05952;

            }

        }

        return $juliandate;

    }

    // }}}

    // {{{ dateNow()

    /**

     * Returns the current local date

     *

     * NOTE: This function retrieves the local date using strftime(),

     * which may or may not be 32-bit safe on your system.

     *

     * @param string $format  the string indicating how to format the output

     *

     * @return string  the current date in the specified format

     *

     * @access public

     * @static

     */

    function dateNow($format = DATE_CALC_FORMAT)

    {

        return strftime($format, time());

    }

    // }}}

    // {{{ getYear()

    /**

     * Returns the current local year in format CCYY

     *

     * @return string  the current year in four digit format

     *

     * @access public

     * @static

     */

    function getYear()

    {

        return Date_Calc::dateNow('%Y');

    }

    // }}}

    // {{{ getMonth()

    /**

     * Returns the current local month in format MM

     *

     * @return string  the current month in two digit format

     *

     * @access public

     * @static

     */

    function getMonth()

    {

        return Date_Calc::dateNow('%m');

    }

    // }}}

    // {{{ getDay()

    /**

     * Returns the current local day in format DD

     *

     * @return string  the current day of the month in two digit format

     *

     * @access public

     * @static

     */

    function getDay()

    {

        return Date_Calc::dateNow('%d');

    }

    // }}}

    // {{{ julianDate()

    /**

     * Returns number of days since 31 December of year before given date

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the julian date for the date

     *

     * @access public

     * @static

     */

    function julianDate($day = 0, $month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        $days = array(0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334);

        $julian = ($days[$month - 1] + $day);

        if ($month > 2 && Date_Calc::isLeapYear($year)) {

            $julian++;

        }

        return $julian;

    }

    // }}}

    // {{{ getWeekdayFullname()

    /**

     * Returns the full weekday name for the given date

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return string  the full name of the day of the week

     *

     * @access public

     * @static

     */

    function getWeekdayFullname($day = 0, $month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        $weekday_names = Date_Calc::getWeekDays();

        $weekday = Date_Calc::dayOfWeek($day, $month, $year);

        return $weekday_names[$weekday];

    }

    // }}}

    // {{{ getWeekdayAbbrname()

    /**

     * Returns the abbreviated weekday name for the given date

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     * @param int    $length  the length of abbreviation

     *

     * @return string  the abbreviated name of the day of the week

     *

     * @access public

     * @static

     * @see Date_Calc::getWeekdayFullname()

     */

    function getWeekdayAbbrname($day = 0, $month = 0, $year = 0, $length = 3)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        return substr(Date_Calc::getWeekdayFullname($day, $month, $year),

                      0, $length);

    }

    // }}}

    // {{{ getMonthFullname()

    /**

     * Returns the full month name for the given month

     *

     * @param int    $month   the month

     *

     * @return string  the full name of the month

     *

     * @access public

     * @static

     */

    function getMonthFullname($month)

    {

        $month = (int)$month;

        if (empty($month)) {

            $month = (int)Date_Calc::dateNow('%m');

        }

        $month_names = Date_Calc::getMonthNames();

        return $month_names[$month];

    }

    // }}}

    // {{{ getMonthAbbrname()

    /**

     * Returns the abbreviated month name for the given month

     *

     * @param int    $month   the month

     * @param int    $length  the length of abbreviation

     *

     * @return string  the abbreviated name of the month

     *

     * @access public

     * @static

     * @see Date_Calc::getMonthFullname

     */

    function getMonthAbbrname($month, $length = 3)

    {

        $month = (int)$month;

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        return substr(Date_Calc::getMonthFullname($month), 0, $length);

    }

    // }}}

    // {{{ getMonthFromFullname()

    /**

     * Returns the numeric month from the month name or an abreviation

     *

     * Both August and Aug would return 8.

     *

     * @param string $month  the name of the month to examine.

     *                        Case insensitive.

     *

     * @return integer  the month's number

     *

     * @access public

     * @static

     */

    function getMonthFromFullName($month)

    {

        $month = strtolower($month);

        $months = Date_Calc::getMonthNames();

        while(list($id, $name) = each($months)) {

            if (ereg($month, strtolower($name))) {

                return $id;

            }

        }

        return 0;

    }

    // }}}

    // {{{ getMonthNames()

    /**

     * Returns an array of month names

     *

     * Used to take advantage of the setlocale function to return

     * language specific month names.

     *

     * TODO: cache values to some global array to avoid preformace

     * hits when called more than once.

     *

     * @returns array  an array of month names

     *

     * @access public

     * @static

     */

    function getMonthNames()

    {

        $months = array();

        for ($i = 1; $i < 13; $i++) {

            $months[$i] = strftime('%B', mktime(0, 0, 0, $i, 1, 2001));

        }

        return $months;

    }

    // }}}

    // {{{ getWeekDays()

    /**

     * Returns an array of week days

     *

     * Used to take advantage of the setlocale function to

     * return language specific week days.

     *

     * TODO: cache values to some global array to avoid preformace

     * hits when called more than once.

     *

     * @returns array  an array of week day names

     *

     * @access public

     * @static

     */

    function getWeekDays()

    {

        $weekdays = array();

        for ($i = 0; $i < 7; $i++) {

            $weekdays[$i] = strftime('%A', mktime(0, 0, 0, 1, $i, 2001));

        }

        return $weekdays;

    }

    // }}}

    // {{{ dayOfWeek()

    /**

     * Returns day of week for given date (0 = Sunday)

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the number of the day in the week

     *

     * @access public

     * @static

     */

    function dayOfWeek($day = 0, $month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        if ($month > 2) {

            $month -= 2;

        } else {

            $month += 10;

            $year--;

        }

        $day = (floor((13 * $month - 1) / 5) +

                $day + ($year % 100) +

                floor(($year % 100) / 4) +

                floor(($year / 100) / 4) - 2 *

                floor($year / 100) + 77);

        $weekday_number = $day - 7 * floor($day / 7);

        return $weekday_number;

    }

    // }}}

    // {{{ weekOfYear()

    /**

     * Returns week of the year, first Sunday is first day of first week

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the number of the week in the year

     *

     * @access public

     * @static

     */

    function weekOfYear($day = 0, $month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        $iso    = Date_Calc::gregorianToISO($day, $month, $year);

        $parts  = explode('-', $iso);

        $week_number = intval($parts[1]);

        return $week_number;

    }

    // }}}

    // {{{ quarterOfYear()

    /**

     * Returns quarter of the year for given date

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the number of the quarter in the year

     *

     * @access public

     * @static

     */

    function quarterOfYear($day = 0, $month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        $year_quarter = intval(($month - 1) / 3 + 1);

        return $year_quarter;

    }

    // }}}

    // {{{ daysInMonth()

    /**

     * Find the number of days in the given month

     *

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the number of days the month has

     *

     * @access public

     * @static

     */

    function daysInMonth($month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if ($year == 1582 && $month == 10) {

            return 21;  // October 1582 only had 1st-4th and 15th-31st

        }

        if ($month == 2) {

            if (Date_Calc::isLeapYear($year)) {

                return 29;

             } else {

                return 28;

            }

        } elseif ($month == 4 or $month == 6 or $month == 9 or $month == 11) {

            return 30;

        } else {

            return 31;

        }

    }

    // }}}

    // {{{ weeksInMonth()

    /**

     * Returns the number of rows on a calendar month

     *

     * Useful for determining the number of rows when displaying a typical

     * month calendar.

     *

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     *

     * @return int  the number of weeks the month has

     *

     * @access public

     * @static

     */

    function weeksInMonth($month = 0, $year = 0)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        $FDOM = Date_Calc::firstOfMonthWeekday($month, $year);

        if (DATE_CALC_BEGIN_WEEKDAY==1 && $FDOM==0) {

            $first_week_days = 7 - $FDOM + DATE_CALC_BEGIN_WEEKDAY;

            $weeks = 1;

        } elseif (DATE_CALC_BEGIN_WEEKDAY==0 && $FDOM == 6) {

            $first_week_days = 7 - $FDOM + DATE_CALC_BEGIN_WEEKDAY;

            $weeks = 1;

        } else {

            $first_week_days = DATE_CALC_BEGIN_WEEKDAY - $FDOM;

            $weeks = 0;

        }

        $first_week_days %= 7;

        return ceil((Date_Calc::daysInMonth($month, $year)

                     - $first_week_days) / 7) + $weeks;

    }

    // }}}

    // {{{ getCalendarWeek()

    /**

     * Return an array with days in week

     *

     * @param int    $day     the day of the month, default is current local day

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     * @param string $format  the string indicating how to format the output

     *

     * @return array $week[$weekday]

     *

     * @access public

     * @static

     */

    function getCalendarWeek($day = 0, $month = 0, $year = 0,

                             $format = DATE_CALC_FORMAT)

    {

        if (empty($year)) {

            $year = Date_Calc::dateNow('%Y');

        }

        if (empty($month)) {

            $month = Date_Calc::dateNow('%m');

        }

        if (empty($day)) {

            $day = Date_Calc::dateNow('%d');

        }

        $week_array = array();

        // date for the column of week

        $curr_day = Date_Calc::beginOfWeek($day, $month, $year,'%E');

        for ($counter = 0; $counter <= 6; $counter++) {

            $week_array[$counter] = Date_Calc::daysToDate($curr_day, $format);

            $curr_day++;

        }

        return $week_array;

    }

    // }}}

    // {{{ getCalendarMonth()

    /**

     * Return a set of arrays to construct a calendar month for the given date

     *

     * @param int    $month   the month, default is current local month

     * @param int    $year    the year in four digit format, default is current local year

     * @param string $format  the string indicating how to format the output

     *

     * @return array $month[$row][$col]

     *

     * @access public

     * @static

     */

    function getCalendarMonth($month = 0, $year = 0,

                              $format = DATE_CALC_FORMAT)