Documentation

# datenum

Convert date and time to serial date number

The `datenum` function creates a numeric array that represents each point in time as the number of days from January 0, 0000. The numeric values also can represent elapsed time in units of days. However, the best way to represent points in time is by using the `datetime` data type. The best way to represent elapsed time is by using the `duration` or `calendarDuration` data types.

## Syntax

``DateNumber = datenum(t)``
``DateNumber = datenum(DateString)``
``DateNumber = datenum(DateString,formatIn)``
``DateNumber = datenum(DateString,PivotYear)``
``DateNumber = datenum(DateString,formatIn,PivotYear)``
``DateNumber = datenum(DateVector)``
``DateNumber = datenum(Y,M,D)``
``DateNumber = datenum(Y,M,D,H,MN,S)``

## Description

example

````DateNumber = datenum(t)` converts the datetime or duration values in the input array `t` to serial date numbers.A serial date number represents the whole and fractional number of days from a fixed, preset date (January 0, 0000) in the proleptic ISO calendar.```
````DateNumber = datenum(DateString)` converts text representing dates and times to serial date numbers. If the format used in the text is known, specify the format as `formatIn`. Syntaxes without `formatIn` are significantly slower than syntaxes that include it.```

example

````DateNumber = datenum(DateString,formatIn)` uses `formatIn` to interpret the dates and times represented by `DateString`. ```
````DateNumber = datenum(DateString,PivotYear)` uses `PivotYear` to interpret text that specifies the year as two characters. If the format used in the text is known, specify the format as `formatIn`. Syntaxes without `formatIn` are significantly slower than syntaxes that include it.```

example

````DateNumber = datenum(DateString,formatIn,PivotYear)` uses `formatIn` to interpret the dates and times represented by `DateString`, and `PivotYear` to interpret text that specifies the year as two characters. You can specify `formatIn` and `PivotYear` in either order.```

example

````DateNumber = datenum(DateVector)` converts date vectors to serial date numbers, and returns a column vector of `m` date numbers, where `m` is the total number of date vectors in `DateVector`.```

example

````DateNumber = datenum(Y,M,D)` returns the serial date numbers for corresponding elements of the `Y`, `M`, and `D` (year, month, day) arrays. The arrays must be of the same size (or any can be a scalar). You also can specify the input arguments as a date vector, `[Y,M,D]`.```
````DateNumber = datenum(Y,M,D,H,MN,S)` additionally returns the serial date numbers for corresponding elements of the `H`, `MN`, and `S` (hour, minute, and second) arrays. The arrays must be of the same size (or any can be a scalar). You also can specify the input arguments as a date vector, `[Y,M,D,H,MN,S]`.```

## Examples

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```format long t = [datetime('now');datetime('tomorrow')]```
```t = 2x1 datetime array 13-Apr-2019 00:05:47 14-Apr-2019 00:00:00 ```
`DateNumber = datenum(t)`
```DateNumber = 2×1 105 × 7.375280040174626 7.375290000000000 ```
```DateString = '19-May-2001'; formatIn = 'dd-mmm-yyyy'; datenum(DateString,formatIn)```
```ans = 730990 ```

`datenum` returns a date number for text representing a date with the format `'dd-mmm-yyyy'`.

Pass several dates as character vectors in a cell array. All input dates must use the same format.

```DateString = {'09/16/2007';'05/14/1996';'11/29/2010'}; formatIn = 'mm/dd/yyyy'; datenum(DateString,formatIn)```
```ans = 3×1 733301 729159 734471 ```

Convert text representing a date to a serial date number using the default pivot year.

`n = datenum('12-jun-17','dd-mmm-yy')`
```n = 736858 ```

The text that represents this date number is `'12-Jun-2017'`.

Convert the same text to a serial date number using 1400 as the pivot year.

`n = datenum('12-jun-17','dd-mmm-yy',1400)`
```n = 517712 ```

The text that represents this date number is `'12-Jun-1417'`.

`datenum([2009,4,2,11,7,18])`
```ans = 7.3387e+05 ```

Convert a date specified by year, month and day values to a serial date number.

`n = datenum(2001,12,19)`
```n = 731204 ```

## Input Arguments

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Dates and times, specified as an array of datetime or duration values. The `datenum` function does not account for time zone information in `t` and does not adjust datetime values that occur during Daylight Saving Time. That is, `datenum` treats the `TimeZone` property of `datetime` arrays as empty and converts the remaining date and time information to a serial date number.

Data Types: `datetime` | `duration`

Date vectors, specified as an `m`-by-6 or `m`-by-3 matrix containing `m` full or partial date vectors, respectively. A full date vector has six elements, specifying year, month, day, hour, minute, and second, in that order. A partial date vector has three elements, specifying year, month, and day, in that order. Each element of `DateVector` must be a positive or negative integer value except for the seconds element, which can be fractional. If an element falls outside the conventional range, `datenum` adjusts both that date vector element and the previous element. For example, if the minutes element is `70`, then `datenum` adjusts the hours element by `1` and sets the minutes element to `10`. If the minutes element is -`15`, then `datevec` decreases the hours element by `1` and sets the minutes element to `45`. Month values are an exception. The `datenum` function sets month values less than `1` to `1`.

Example: `[2003,10,24,12,45,07]`

Data Types: `double`

Text representing dates and times, specified as a character array where each row contains text representing one point in time, as a cell vector of character vectors, or as a string vector. All rows of a character array, or all elements of a cell vector or string vector, must have the same format.

Example: `'24-Oct-2003 12:45:07'`

Example: `['19-Sep-2013';'20-Sep-2013';'21-Sep-2013']`

Example: `{'15-Oct-2010' '20-Nov-2012'}`

If the format used in the text is known, you should also specify `formatIn`. If you do not specify `formatIn`, then `DateString` must be in one of the following formats.

Format of Text Representing Dates and Times

Example

`'dd-mmm-yyyy HH:MM:SS'`

`01-Mar-2000 15:45:17`

`'dd-mmm-yyyy'`

`01-Mar-2000`

`'mm/dd/yyyy'`

`03/01/2000`

`'mm/dd/yy'`

`03/01/00 `

`'mm/dd'`

`03/01`

`'mmm.dd,yyyy HH:MM:SS'`

`Mar.01,2000 15:45:17`

`'mmm.dd,yyyy'`

`Mar.01,2000`

`'yyyy-mm-dd HH:MM:SS'`

`2000-03-01 15:45:17`

`'yyyy-mm-dd'`

`2000-03-01`

`'yyyy/mm/dd'`

`2000/03/01`

`'HH:MM:SS'`

`15:45:17`

`'HH:MM:SS PM'`

`3:45:17 PM`

`'HH:MM'`

`15:45`

`'HH:MM PM'`

`3:45 PM`

### Note

The symbolic identifiers describing date and time formats are different from those that describe the display formats of `datetime` arrays.

Certain formats might not contain enough information to convert text representations of dates and times. In those cases, hours, minutes, and seconds default to 0, days default to 1, months default to January, and years default to the current year. `datevec` and `datenum` consider two-character years (e.g., `'79'`) to fall within the 100-year range centered around the current year.

When you do not specify `formatIn`, note the following:

• For the formats that specify the month as two digits (`mm`), the month value must not be greater than 12.

• However, for the format `'mm/dd/yy'`, if the first entry in the text is greater than 12 and the second entry is less than or equal to 12, then `datenum` considers the text to be in `'yy/mm/dd'` format.

Format of the input text representing dates and times, specified as a character vector or string scalar of symbolic identifiers.

Example: `'dddd, mmm dd, yyyy'`

The following table shows symbolic identifiers that you can use to construct the `formatIn` character vector. You can include characters such as a hyphen, space, or colon to separate the fields.

### Note

The symbolic identifiers describing date and time formats are different from the identifiers that describe the display formats of `datetime` arrays.

Symbolic Identifier

Description

Example

`yyyy`

Year in full

`1990`, `2002`

`yy`

Year in two digits

`90`, `02`

`QQ`

Quarter year using letter `Q` and one digit

`Q1`

`mmmm`

Month using full name

`March`, `December`

`mmm`

Month using first three letters

`Mar`, `Dec`

`mm`

Month in two digits

`03`, `12`

`m`

Month using capitalized first letter

`M`, `D`

`dddd`

Day using full name

`Monday`, `Tuesday`

`ddd`

Day using first three letters

`Mon`, `Tue`

`dd`

Day in two digits

`05`, `20`

`d`

Day using capitalized first letter

`M`, `T`

`HH`

Hour in two digits
(no leading zeros when symbolic identifier `AM` or `PM` is used)

`05`, `5` `AM`

`MM`

Minute in two digits

`12`, `02`

`SS`

Second in two digits

`07`, `59`

`FFF`

Millisecond in three digits

`057`

`AM or PM`

`AM` or `PM` inserted in text representing time

`3:45:02` `PM`

The `formatIn` value must follow these guidelines:

• You cannot specify any field more than once. For example, you cannot use `'yy-mmm-dd-m'` because it has two month identifiers. The one exception to this is that you can combine one instance of `dd` with one instance of any of the other day identifiers. For example, `'dddd mmm dd yyyy'` is a valid input.

• When you use `AM` or `PM`, the `HH` field is also required.

• You only can use `QQ` alone or with a year specifier.

Start year of the 100-year date range in which a two-character year resides, specified as an integer. Use a pivot year to interpret dates that specify the year as two characters.

If `formatIn` contains the time of day, the pivot year is computed from the current time of the current day, month, and year. Otherwise it is computed from midnight of the current day, month, and year.

Example: `2000`

### Note

If the input date format specifies a four-character year, then the last two characters are truncated, and the first two characters specify the year. For example, if the date and pivot year are specified as `('25122015','ddmmyyyy',2000)`, then the resulting date is `25-12-2020`, not `25-12-2015`.

Data Types: `double`

Year, month, and day arrays specified as numeric arrays. These arrays must be the same size, or any one can be a scalar. The values in `Y,M,D` must be integer values.

If `Y,M,D` are all scalars or all column vectors, you can specify the input arguments as a date vector, `[Y,M,D]`.

Example: `2003,10,24`

Data Types: `double`

Year, month, day, hour, minute, and second arrays specified as numeric arrays. These arrays must be the same size, or any one can be a scalar. `datenum` does not accept milliseconds as a separate input, but as a fractional part of the seconds input, `S`. The values in `Y,M,D,H,MN` must be integer values.

If `Y,M,D,H,MN,S` are all scalars or all column vectors, you can specify the input arguments as a date vector, `[Y,M,D,H,MN,S]`.

Example: `2003,10,24,12,45,07.451`

Data Types: `double`

## Output Arguments

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Serial date numbers, returned as a column vector of length `m`, where `m` is the total number of input date vectors or character vectors representing dates and times.

## Tips

• To create arbitrarily shaped output, use the `datenum(Y,M,D)` and `datenum(Y,M,D,H,MN,S)` syntaxes. The `datenum(DateVector)` syntax creates only a column vector of date numbers.

`datenum(2013,[1 3; 2 4],ones(2,2))`
```ans = 735235 735294 735266 735325```

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