Each formula on this website is given a unique identification number. As
the Mathematical Functions Site expands and more information is added, the
of a given formula within its group may change or the group might be split
into several subgroups. However, the unique identification number will
All unique identification numbers will have the following form, with each
x representing a digit between 0 and 9.
Each group in the citation number specifies a portion of the hierarchy in
which the formula resides.
First set of two digits: Function category
Second set of two digits: Function within the category
Third two digits: Section
Next four digits: Formula within section
Last two digits: Revision number
The citation number is then incorporated into a corresponding URL that can
be used to directly reference a particular formula. We recommend that you
use these unique reference URLs for any citation purposes. These reference
URLs will have the following form, in which each italicized letter represents
Some examples of working citation numbers are:
If you only have a citation number, it can be entered into the citation
search to bring up its corresponding formula. To see the formula
associated with a given citation number, enter the citation number into
the search form that appears at the top right of the front page.