# IMSL_DATETODAYS

The IMSL_DATETODAYS function computes the number of days from January 1, 1900, to the given date.

Note: This routine requires an IDL Analyst license. For more information, contact your Exelis VIS sales or technical support representative.

The IMSL_DATETODAYS function returns the number of days from January 1, 1900, to the given date and returns negative values for days prior to January 1, 1900. A negative year can be used to specify B.C. Input dates in year 0 and for October 5, 1582, through October 14, 1582, inclusive, do not exist; consequently, in these cases, IMSL_DATETODAYS issues an error.

The Gregorian calendar starts the first day after October 4, 1582, which became October 15, 1582. Prior to that, the Julian calendar was in use.

## Examples

### Example 1

The following example uses IMSL_DATETODAYS to compute the number of days from January 15, 1986, to February 28, 1986.

d0 = IMSL_DATETODAYS(15, 1, 1986)

d1 = IMSL_DATETODAYS(28, 2, 1986)

PM, d1 - d0, TITLE = 'Number of days from 1/15/86 to 2/28/86'

Number of days from 1/15/86 to 2/28/86

44

## Syntax

Result = IMSL_DATETODAYS([day[, month[, year]]])

## Return Value

Number of days from January 1, 1900, to the given date. If negative, it indicates the number of days prior to January 1, 1900.

## Arguments

### day

Day of the input date.

### month

Month of the input date.

### year

Year of the input date. The year 1950 corresponds to the year 1950 A.D., and the year 50 corresponds to year 50 A.D.

## Keywords

None

## Version History

6.4 | Introduced

## See Also

IMSL_DAYSTODATE