decyear

Decimal year calculator

Syntax

```dy = decyear(v) dy = decyear(s,f) dy = decyear(y,mo,d) dy = decyear([y,mo,d]) dy = decyear(y,mo,d,h,mi,s) dy = decyear([y,mo,d,h,mi,s]) ```

Description

`dy = decyear(v)` converts one or more date vectors, `v`, into decimal year, `dy`. Input `v` can be an `m`-by-6 or `m`-by-3 matrix containing `m` full or partial date vectors, respectively. `decyear` returns a column vector of `m` decimal years.

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.

`dy = decyear(s,f)` converts one or more date character vectors, `s`, to decimal year, `dy`, using format `f`. `s` can be a character array, where each row corresponds to one date, or a one-dimensional cell array of character vectors. `decyear` returns a column vector of `m` decimal years, 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 the `datestr` function. `decyear` 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.

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

`dy = decyear(y,mo,d)` and `dy = decyear([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.

`dy = decyear(y,mo,d,h,mi,s)` and `dy = decyear([y,mo,d,h,mi,s])` return the decimal year 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 decimal year for May 24, 2005:

```dy = decyear('24-May-2005','dd-mmm-yyyy') dy = 2.0054e+003```

Calculate decimal year for December 19, 2006:

```dy = decyear(2006,12,19) dy = 2.0070e+003```

Calculate decimal year for October 10, 2004, at 12:21:00 p.m.:

```dy = decyear(2004,10,10,12,21,0) dy = 2.0048e+003```

Assumptions and Limitations

The calculation of decimal year does not take into account leap seconds.