<p>
These are examples that illustrate a 'before' and 'after' version
of a one-dimensional Newton method code for solving an equation
f(x)=0.  The before version, test.f, has statement labels and uses a
withdrawn feature of Fortran, alternate return subprogram arguments.
These implement reverse communication.  This constuct provides the
function and derivative values required by Newton's method.
</p>
<p>
The after version, test2.f90, uses the same logic as test.f, but has
removed the alternate returns and the statement labels.  In their
place is a select case construct based on an additional integer flag.
</p>

<p>
Two executables may be generated using the makefile
<ul>
<li> test uses test.f
<li> test2 uses test2.f90
</ul>
</p>
<h3> Sample output from test</h3>
<pre>
Solution and absolute error:
  0.9000E+00  0.5960E-07
</pre>
<h3> Sample output from test2</h3>
<pre>
Solution and absolute error:
  0.9000E+00  0.5960E-07
</pre>