Julian day number
A Julian day number is a continuous count of days since noon on January 1, 4713 BCE, in the Julian calendar, optionally including a fractional part for the time of day.
Software Design for Python Programmers
A Julian day number is a count of days elapsed since noon on January 1, 4713 BCE, in the Gregorian calendar, optionally including a fractional part for the time of day.
- How it is used
- Simplifies date arithmetic by representing dates as elapsed-day counts instead of Gregorian components.
- How deep it goes
- Defines the epoch and demonstrates conversion algorithms, while noting their complexity and repeated getter cost.
- Examples
- Uses Julian day numbers 0, 2,440,000, and 3,000,000 to verify conversions against Gregorian dates.
- What you can do after
- Apply it via a Date class to add days and calculate differences efficiently.
Read how Software Design for Python Programmers explains julian day number →
Object-Oriented Software Design in C++
A Julian day number is a numeric count of days elapsed since noon on January 1, 4713 BCE, in the Gregorian calendar, with fractional values representing times between noons.
- How it is used
- Simplifies date arithmetic by representing each day with a numeric count.
- How deep it goes
- Defines the count and applies it inside Date, but defers the complicated Gregorian conversion algorithms.
- Examples
- Demonstrates day differences, date addition, September 2, 2025, April 3, 2027, and the 1968 conversion milestone.
- What you can do after
- Apply it via a Date class to calculate day differences and add days efficiently.
Read how Object-Oriented Software Design in C++ explains julian day number →
Related concepts
- date arithmeticaddresses · The calculation of dates and intervals by adding, subtracting, or otherwise manipulating time values.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.