# mjuliandate

Modified Julian date calculator

## Description

example

mjd = mjuliandate(datetime) converts one or more datetime arrays to modified Julian date, mjd. Modified Julian dates begin at midnight rather than noon, and the first two digits of its corresponding Julian date are removed.

mjd = mjuliandate(dateVector) converts one or more date vectors, dateVector, to modified Julian date, mjd.

mjd = mjuliandate(dateCharacterVector,format) converts one or more date character vectors, dateCharacterVector, to modified Julian date, mjd, using format format.

example

mjd = mjuliandate(year,month,day,'Action'=value) and mjd = mjuliandate([year,month,day],'Action'=value) return the modified Julian date for corresponding elements of the year,month,day arrays.

mjd = mjuliandate(year,month,day,hour,minute,second,'Action'=value) and mjd = mjuliandate([year,month,day,hour,minute,second],'Action'=value) return the modified Julian date for corresponding elements of the year,month,day,hour,minute,second arrays. Specify the six arguments as 1-D arrays of the same length or scalar values.

## Examples

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Calculate the modified Julian date for February 4, 2016 from datetime array.

dt = datetime('04-02-2016','InputFormat','dd-MM-yyyy')
jd = mjuliandate(dt)

dt =
datetime

04-Feb-2016

jd =
57422

Calculate the modified Julian date for May 24, 2005 using date character version and dd-mm-yyyy format:

mjd = mjuliandate('24-May-2005','dd-mmm-yyyy')
mjd =
53514

Calculate modified Julian date for December 19, 2006 from year, month, and day inputs:

mjd = mjuliandate(2006,12,19)
mjd =
54088

Calculate the modified Julian date for October 10, 2004, at 12:21:00 p.m. using year, month, day, hour, month, and second inputs:

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

mjd =
5.3289e+004

## Input Arguments

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datetime array, specified as an m-by-1 array or 1-by-m array.

Full or partial date vector, specified as an m-by-6 or m-by-3 matrix containing m full or partial date vectors, respectively:

• Full date vector — Contains six elements specifying the year, month, day, hour, minute, and second

• Partial date vector — Contains three elements specifying the year, month, and day

Data Types: double

Date character vector, specified as a character array, where each row corresponds to one date, or a 1-D array cell array of character vectors.

Data Types: char | string

Date format, specified as a character vector, string scalar, or integer. All dates in dateCharacterVector must have the same format and use the same date format symbols as the datenum function.

mjuliandate 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.

Data Types: char | string

Year, specified as a positive scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: char | string

Month, specified as a positive or negative scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: double

Day, specified as a positive or negative scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: double

Hour, specified as a positive or negative scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: double

Minute, specified as a positive or negative scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: double

Second, specified as a positive or negative scalar or 1-D array.

#### Dependencies

Depending on the syntax, specify year, month, and day or year, month, day, hour, minute, and second as 1-D arrays of the same length or scalar values.

Data Types: double

Action for noninteger decimal date input for year, month, day, hour, and minute, specified as:

• 'Error' — Displays error and total number of noninteger date values.

• 'Warning' — Displays warning and total number of adjusted noninteger date values. The function adjusts the noninteger value to its integer equivalent before calculating the value.

• 'None' — Does not display warning or error. The function adjusts the noninteger value to its integer equivalent before calculating the value.

Data Types: char | string

## Output Arguments

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Modified Julian date, returned as a column vector of m modified Julian dates, which are the number of days and fractions since noon Universal Time on January 1, 4713 BCE.

• m-by-6 column vector — Contains six elements specifying the year, month, day, hour, minute, and second

• m-by-3 column vector — Contains three elements specifying the year, month, and day

#### Dependencies

The output format depends on the input format:

Input Syntaxdy Format
mjd = mjuliandate(dateVector)m-by-6 column vector or m-by-3 column vector of m modified Julian dates.
mjd = mjuliandate(dateCharacterVector,format)Column vector of m modified Julian dates, where m is the number of character vectors in dateCharacterVector.

## Limitations

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

## Version History

Introduced in R2006b

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