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mjuliandate

Modified Julian date calculator

Syntax

mjd = mjuliandate(v)
mjd = mjuliandate(s,f)
mjd = mjuliandate(y,mo,d)
mjd = mjuliandate([y,mo,d])
mjd = mjuliandate(y,mo,d,h,mi,s)
mjd = mjuliandate([y,mo,d,h,mi,s])

Description

mjd = mjuliandate(v) converts one or more date vectors, v, into modified Julian date, mjd. Input v can be an m-by-6 or m-by-3 matrix containing m full or partial date vectors, respectively. mjuliandate returns a column vector of m modified Julian dates. Modified Julian dates begin at midnight rather than noon, and the first two digits of its corresponding Julian date are removed.

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.

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

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

If a 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.

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

mjd = mjuliandate(y,mo,d) and mjd = mjuliandate([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.

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

Examples

Calculate the modified Julian date for May 24, 2005:

`mjd = mjuliandate('24-May-2005','dd-mmm-yyyy')`
```mjd =

53514```

Calculate the modified Julian date for December 19, 2006:

`mjd = mjuliandate(2006,12,19)`
```mjd =

54088```

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

```mjd = mjuliandate(2004,10,10,12,21,0)
```
```mjd =

5.3289e+004```

Assumptions and Limitations

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

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