The primary purpose of the DATA statement is to give names to<br>
constants; instead of referring to pi as 3.141592653589793 at every<br>
appearance, the variable PI can be given that value with a DATA<br>
statement and used instead of the longer form of the constant.  This<br>
also simplifies modifying the program, should the value of pi change.<br>
                -- FORTRAN manual for Xerox Computers<br>