Summary: Undergraduate Research Opportunity
Programme in Science
CALENDARS, INTERPOLATION,
GNOMONS AND ARMILLARY
SPHERES IN THE WORK OF
GUO SHOUJING (1231­1314)
NG SAY TIONG
HELMER ASLAKSEN
Department of Mathematics
National University of Singapore
Semester I, 2000/2001
Introduction
In today's modern society, when we talk about calendars, almost every-
one will associate it with the Gregorian calendar, which is the calendar most
commonly used today. The Gregorian calendar is a solar calendar, which
follows the movement of the sun. It uses days to approximate the length of
the tropical year. A tropical year can be thought of as the time from one
spring equinox to the next. A year in the Gregorian calendar will approxi-
mate the time the earth takes to complete a revolution around the sun. A
year in a Gregorian calendar consists of 365 days (in most cases) divided into

Source: Aslaksen, Helmer - Department of Mathematics, National University of Singapore

Collections: Mathematics