Graph Software for Scientists and Engineers

• Home
• Features
• Buy DPlot
• Forums
• FAQ
• Contact
• Blog
• Downloads

Trigonometric and General Math Functions

This page provides a brief description of the functions available in the Y=f(X) command and similar commands. For a more detailed description of each function, click on the function name. Function names are not case specific.

Please note: All dates taken as input arguments to these functions are Excel 1900 date system serial numbers, the internal date format used throughout DPlot.

Excel date system

DPlot uses Microsoft Excel for Windows 1900 Date System serial numbers for date values, with one exception: Excel limits date input to January 1, 1900 through December 31, 2078. DPlot allows dates between October 15, 1582 and December 31, 9999.

In this system a serial number of 1 corresponds to January 1, 1900. The following code converts a month, day, and year to the Excel 1900 Date System serial number for years between 1900 and 2099, inclusive.

if( Year >= 1900 && Year <= 2099 )
{
    if( Month > 2 )
        SerNum=floor(365.25*Year)+floor(30.6001*(Month+1))+Day-694037;
    else
        SerNum=floor(365.25*(Year-1))+floor(30.6001*(Month+13))+Day-694037;
}