 the function dpsw on (a, b) to absolute
accuracy tol &gt; 0.</p>
<p>the function in time is given by rpar with ipar points</p>
<p>I removed the optional printing routine part of the code, 
to make it easier to read. I also moved both nval, etol
as normal variables inside the routine.</p>
<p>nval = number of function calls made by routine
etol = approximate magnitude of the error of the result</p>
<dl>
<dt>NB:  function set_xint is called once before  xint  to</dt><dd><p>provide quadrature samples and weigh