juliandate

Julian date calculator

Syntax

```jd = juliandate(v) jd = juliandate(s,f) jd = juliandate(y,mo,d) jd = juliandate([y,mo,d]) jd = juliandate(y,mo,d,h,mi,s) jd = juliandate([y,mo,d,h,mi,s]) ```

Description

`jd = juliandate(v)` converts one or more date vectors, `v`, into Julian date, `jd`. Input `v` can be an `m`-by-6 or `m`-by-3 matrix containing `m` full or partial date vectors, respectively. `juliandate` returns a column vector of `m` Julian dates, which are the number of days and fractions since noon Universal Time on January 1, 4713 BCE.

A date vector contains six elements, specifying year, month, day, hour, minute, and second. A partial date vector has three elements, specifying year, month, and day. Each element of `v` must be a positive double-precision number.

`jd = juliandate(s,f)` converts one or more dates, `s`, into Julian date, `jd`, using format `f`. `s` can be a character array, where each row corresponds to one date character vector, or a one-dimensional cell array of character vectors. `juliandate` returns a column vector of `m` Julian dates, where `m` is the number of character vectors in `s`.

All of the dates in `s` must have the same format `f`, composed of the same date format symbols as `datestr`. `juliandate` does not accept formats containing the letter `Q`.

If the format does not contain enough information to compute a date number, then:

• Hours, minutes, and seconds default to 0.

• Days default to 1.

• Months default to January.

• Years default to the current year.

Dates with two-character years are interpreted to be within 100 years of the current year.

`jd = juliandate(y,mo,d)` and `jd = juliandate([y,mo,d])` return the decimal year for corresponding elements of the `y,mo,d` (year,month,day) arrays. Specify `y`, `mo`, and `d` as one-dimensional arrays of the same length or scalar values.

`jd = juliandate(y,mo,d,h,mi,s)` and `jd = juliandate([y,mo,d,h,mi,s])` return the Julian dates for corresponding elements of the `y,mo,d,h,mi,s` (year,month,day,hour,minute,second) arrays. Specify the six input arguments as either one-dimensional arrays of the same length or scalar values.

Examples

Calculate Julian date for May 24, 2005:

`jd = juliandate('24-May-2005','dd-mmm-yyyy')`
```jd = 2.4535e+006```

Calculate Julian date for December 19, 2006:

`jd = juliandate(2006,12,19)`
```jd = 2.4541e+006```

Calculate Julian date for October 10, 2004, at 12:21:00 p.m.:

`jd = juliandate(2004,10,10,12,21,0)`
```jd = 2.4533e+006```

Assumptions and Limitations

This function is valid for all common era (CE) dates in the Gregorian calendar.

The calculation of Julian date does not take into account leap seconds.