From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 21 Aug 2016 20:56:56 +0000 (+0100)
Subject: compute-scottish-stv: fixes
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=appendix-a6.git;a=commitdiff_plain;h=4642960b13763e24dcb10ab40cd650e12e1f84fe;ds=sidebyside

compute-scottish-stv: fixes
---

diff --git a/compute-scottish-stv b/compute-scottish-stv
index d92db96..e09f1eb 100755
--- a/compute-scottish-stv
+++ b/compute-scottish-stv
@@ -32,6 +32,9 @@ our $stage=0;
 our $quota;
 our %tie;
 
+our $DIGS = 5;
+our $F = (new Math::BigRat 10)->bpow($DIGS);
+
 open DEBUG, ">.compute.log" or die $!;
 DEBUG->autoflush(1);
 
@@ -156,6 +159,30 @@ sub sortballots (@) {
     }
 }
 
+sub floor ($) {
+    my ($v) = @_;
+    $v = new Math::BigRat $v; # we need a copy
+    return $v->bfloor();
+}
+
+sub sv ($) {
+    my ($in) = @_;
+    my $v = new Math::BigRat $in; # just in case
+    my $intpart = floor($v);
+    my $frac = $v - $intpart;
+    my $good = floor($frac * $F);
+    my $bad = $frac * $F - $good;
+    my $s = sprintf "%7d", $intpart;
+    if ($frac) {
+	$s .= sprintf ".%0${DIGS}d", $good;
+	$s .= sprintf "%-4s", ($bad ? "+$bad" : "");
+    } else {
+	$s .= sprintf " %${DIGS}s%4s", '', '';
+    }
+#print STDERR "# $in => $s # (intpart=$intpart frac=$frac)\n";
+    return $s;
+}
+
 sub prf {
     my $fmt = shift;
     printf "stage %d: ".$fmt, $stage, @_;
@@ -172,15 +199,15 @@ sub countballots () {
 
     foreach my $c (reverse sort total_history_cmp
 		   grep { !$_->{NonCont} } values %cands) {
-	prf "candidate %-10s: %10s votes\n", $c->{Cand}, $c->{Total};
+	prf "candidate %-10s: %s votes\n", $c->{Cand}, sv $c->{Total};
     }
 }
 
 sub computequota () {
     my $totalvalid = 0/1;
     $totalvalid += $_->{Total} foreach values %cands;
-    $quota = ($totalvalid / (1 + $seats)) -> bfloor();
-    prf "quota %10s\n", $quota;
+    $quota = floor($totalvalid / (1 + $seats));
+    prf "quota %s\n", sv $quota;
 }
 
 sub total_history_cmp () {
@@ -304,15 +331,14 @@ for (;;) {
 	my $B = $c->{Total};
 	my %tspr;
 
-	prf "surplus %10s\n", $surplus;
+	prf "surplus %s\n", sv $surplus;
 
 	foreach my $v (@{ $c->{Votes} }) {
 	    my $previously = $v->{TransferredSurplus};
 	    push @$previously, $c->{Cand};
 
 	    my $A = $surplus * $v->{Weight};
-	    my $F = 100000;
-	    my $xfervalue = ((($A * $F) / $B) -> bfloor() ) / $F;
+	    my $xfervalue = floor(($A * $F) / $B) / $F;
 	    # SLGEO 48(3): we do arithmetic to 5 d3ecimal places,
 	    # but always rounding down
 	    votelog $v, "transferring with value $xfervalue (A=$A B=$B)";
@@ -322,8 +348,8 @@ for (;;) {
 		die unless $tspr{"@$previously"} == $xfervalue;
 	    } else {
 		$tspr{"@$previously"} = $xfervalue;
-		prf "transfer value of ballots %s: %10s\n",
-		    "@$previously", $xfervalue;
+		prf "transfer value of ballots %s: %s\n",
+		    "@$previously", sv $xfervalue;
 	    }
 	}
 	sortballots @{ $c->{Votes} };