protect when n is too small for the calculation, still need documenta…

…tion improvement
bioperl · Nov 15, 2011 · c0f50eb · c0f50eb
1 parent 68d033c
commit c0f50eb
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/Bio/PopGen/Statistics.pm b/Bio/PopGen/Statistics.pm
@@ -277,6 +277,10 @@ sub fu_and_li_D {
 sub fu_and_li_D_counts {
     my ($self,$n,$seg_sites, $external_mut) = @_;
     my $a_n = 0;
+    if( $n <= 3 ) {
+	$self->warn("n is $n, too small, must be > 3\n");
+	return;
+    }
     for(my $k= 1; $k < $n; $k++ ) {
 	$a_n += ( 1 / $k );
     }