This is an explanation web page for the program
<a href="extinct.for">extinct.for</a> which is 
archived at <a href="http://ascl.net/">ASCL.net</a> 
under
<a href="http://ascl.net/hakkila990602.html">
hakkila990602.html</a>.

<p>

The routines COSD, SIND, TAND, TAN2D, and the inverses of these
functions are built in to many FORTRAN compilers. For example, they are
standard on many VAXes. However, I taught FORTRAN this past year, and
was kind of disturbed to discover that these functions are not FORTRAN
77 standards. Thus, I really don't know what to tell you about where
they originate. <p>

The routines are easy to write: the only difference between them and the
accepted standards is that their arguments are in degrees rather than in
radians. The routines could just do the conversion and call the accepted
FORTRAN built-in functions. <p>

Example: <p>

     FUNCTION COSD(X) <br>
     Y = X / 57.2957787 <br>
     COSD = COS(Y) <br>
     END <p>

The main reason for not including them is that some compilers may
already have them.  - Dr. Jon Hakkila