/** Generalized Summation **/

/*K: sum; summation; series; generalized summation */
/*A: J Gottschalk */
/*S: University of Western Australia */
/*D: January 1985 */

GenSum_:Tier

/*: GenSum[$exp,{$m,$p,$q}]
	   is the generalized summation defined by
	   Sum[$exp,{$m,$p,$q}]     for $p < $q+1;
	   0                        for $p = $q+1;
          -Sum[$exp,{$m,$q+1,$p-1}] for $p > $q+1. */

GenSum[$x,{$m,$p_=Numbp[$p],$q_=Numbp[$q]}] :: \
                                 Sel[$p < $q+1,Sum[$x,{$m,$p,$q}],\
	                             $p = $q+1,0,\
	                             $p > $q+1,-Sum[$x,{$m,$q+1,$p-1}]]


_XGenSum[Loaded] : 1

