% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/cal_sym454.R
\name{calendar_sym454}
\alias{calendar_sym454}
\alias{cal_sym454}
\title{Symmetry454 time unit classes}
\format{
A civil-based calendar containing Symmetry454 time units.
}
\usage{
cal_sym454
}
\value{
An S3 list of class \code{c("cal_sym454", "mt_calendar")} containing
the named time unit classes of the Symmetry454 calendar. Each unit is
accessible via \code{$} notation and calling it with a step size produces a
time granule (e.g., 1 week granule as \code{cal_sym454$week(1L)}).
}
\description{
Time unit constructors for the Symmetry454 calendar system. These units can be
used with \code{\link[=linear_time]{linear_time()}} to create custom time representations.
}
\details{
The Symmetry454 calendar (Sym454) is a perennial solar calendar proposed by
Dr. Irv Bromberg. It preserves the traditional 12-month structure and 7-day
week, with months arranged in a symmetrical 4-5-4 week pattern per quarter.
Every month starts on Monday and has a whole number of weeks, meaning no
month ever contains a partial week.

The following time units are available in the Symmetry454 calendar (\verb{cal_sym454$}).
\itemize{
\item \code{year()}: Year unit
\item \code{month()}: Month unit
\item \code{week()}: Week unit
\item \code{day()}: Day unit
\item \code{hour()}: Hour unit
\item \code{minute()}: Minute unit
\item \code{second()}: Second unit
\item \code{millisecond()}: Millisecond unit
}
\subsection{Leap years}{

Rather than intercalary days, Symmetry454 uses a \strong{leap week} appended to
December once every 5 or 6 years, making December a 5-week month in leap
years. A year is a leap year if \code{(52 * year + 146) \%\% 293 < 52}.

This yields a mean year of 365 + 71/293 days (approx 365 days, 5 hours, 48
minutes, 56.5 seconds), intentionally slightly shorter than the mean
northward equinoctial year.
}
}
\examples{
# Create a custom time representation using Symmetry454 units
linear_time(
  Sys.time(),
  chronon = cal_sym454$week(1L)
)

}
\seealso{
\code{\link[=linear_time]{linear_time()}} for creating linear time points, and
\url{https://en.wikipedia.org/wiki/Symmetry454} for more calendar details.
}
