Problems with date number format

[John]

In using the "Edit>YYYYMMDDHHMM to Serial..." command, it correctly displays dates after 1900, but anything pre-1900 (e.g., 1850,1860,1870,1880,1890 in the form of 185001010000, etc.) is displayed as ########## in the graph. If I use the "Edit>Edit Data..." menu command, all the dates display correctly. If I'm reading things correctly, I notice the pre-1900 serial numbers (i.e., when displayed in default number format rather than date format) are negative and this is where the above problem occurs.

Hope I'm not missing anything obvious here, but any help would be appreciated.

[DPlotAdmin]

John,
Thanks for pointing the problem out. It is indeed because the Excel serial number system goes negative with pre-1900 dates, but there's no reason DPlot can't handle this correctly. I'll either fix it or sheepishly explain why it can't be done for the next release.

[DPlotAdmin]

The problem is with the "Date and Time" number format, not anything to do with "Edit>YYYYMMDDHHMM to Serial...". If you right-click on the dates along the X axis and choose "Calendar Date" instead of "Date and Time" then you'll get proper pre-1900 dates.

The goof here is that DPlot originally had the same limitations as Excel dates: Jan 1, 1900 through Dec 31, 2078 (just a guess, but MS must have wanted to be able to represent the date as an unsigned 2-byte integer). The "Calendar Date" number format and other date-related features were later modified to accept dates from Oct 15, 1582 to Dec 31, 9999, but the "Date and Time" number format didn't follow suit. This is fixed at my end and will be included in the next release.

Thanks again for pointing out the problem.