From: ian <ian>
Date: Mon, 27 Feb 2006 01:55:51 +0000 (+0000)
Subject: three-resistor combinations - but not very good because too dense so too many pages
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=abe262b1284fd1ce14162d67b589197344619542;p=trains.git

three-resistor combinations - but not very good because too dense so too many pages
---

diff --git a/misc/divider-table.pl b/misc/divider-table.pl
index fbd6c6a..4aa66e2 100755
--- a/misc/divider-table.pl
+++ b/misc/divider-table.pl
@@ -1,11 +1,22 @@
 #!/usr/bin/perl -w
 
+# for three-resistor combinations,
+# ./divider-table.pl -t |atp >ps -p -f Courier5:0.575,0,0,0.7 -B -M 18,15,15,15
+#  and then print on >=600dpi printer, preferably better
+
 use strict;
+use POSIX;
 
 our(@e12) = qw(10 12 15 18 22 27 33 39 47 56 68 82);
 our(@ex24) = qw(11 13 16 20 24 30 36 43 51 62 75 91);
 our(@e24)= sort @e12, @ex24;
 
+our (@series,$three);
+
+"@ARGV" =~ m/^(?:\-(?:t|12|24)+)?$/ or die;
+@series = "@ARGV" =~ m/12/ ? @e12 : @e24;
+$three = "@ARGV" =~ m/t/;
+
 our ($tlin,$tlog,@byrat);
 
 sub thead ($$) {
@@ -51,32 +62,54 @@ sub fracfit ($$) {
 
 sub scan () {
     my ($row,$col,$lin,$log,$rownum);
+    my ($combe,$combo,$combw,$combwe,$den,$denp);
     @byrat = ();
     thead(\$tlin,'X/Y [*10^k]');
     thead(\$tlog,'frac(L(X/Y))');
-    for $col (@e24) {
+    for $col (@series) {
 	chead(\$tlin,$col);
 	chead(\$tlog,$col);
     }
     theadend(\$tlin);
     theadend(\$tlog);
     $rownum= 0;
-    for $row (@e24) {
+    for $row (@series) {
 	rhead(\$tlin,$row);
 	rhead(\$tlog,$row);
-	for $col (@e24) {
-	    $lin= $col*1.0 / $row;
-	    $log= log($lin)/log(10) + 1.0;
-
-	    cell(\$tlin, mul10fit($lin,5));
-	    cell(\$tlog, fracfit($log,5));
-
-	    if ($col < $row) { $lin *= 10; }
-	    next if $row==$col;
-	    push @byrat, { Num => $col,
-			   Den => $row,
-			   Lin => $lin,
-			   Log => $log };
+	for $col (@series) {
+	    for $combo (('', '|', '+')) {
+		next if length($combo) and not $three;
+		for $combw (length($combo) ? @series : ('')) {
+		    for $combe (length($combo) ? (0, 1, 2) : (0,)) {
+			if ($combo eq '') {
+			    $den= $denp= $row;
+			} else {
+			    $combwe= $combw * pow(10, -2 + $combe);
+			    $den= $combo eq '+' ? $row + $combwe :
+				1.0/(1.0/$row + 1.0/$combwe);
+			    $denp= $combw;
+			    $denp =~ s/.{$combe}/$&\./;
+			    $denp= $row.$combo.$denp;
+			    next if grep {
+				abs(fmod(abs(log($_/$den)) + 0.1,
+					 log(10)) - 0.1) < 1e-6
+				} @series;
+			}
+			$lin= $col*1.0 / $den;
+			while ($lin < 1000) { $lin *= 10; }
+			$log= log($lin)/log(10) + 1.0;
+
+			cell(\$tlin, mul10fit($lin,5));
+			cell(\$tlog, fracfit($log,5));
+
+			next if $row==$col;
+			push @byrat, { Num => $col,
+				       Den => $denp,
+				       Lin => $lin,
+				       Log => $log };
+		    }
+		}
+	    }
 	}
 	rend(\$tlin,$rownum);
 	rend(\$tlog,$rownum);
@@ -97,10 +130,24 @@ sub ptable ($) {
 
 sub sortbyrat () {
     @byrat= sort {
-	$a->{Lin} <=> $b->{Lin}
+	$a->{Lin} <=> $b->{Lin} or
+	$a->{Num} <=> $b->{Num}
     } @byrat;
 }
 
+sub uniqbyrat () {
+    my ($last,$i,$t,@byratnew);
+    @byratnew= ();
+    $last= 'x';
+    for $i (@byrat) {
+	$t= "$i->{Num} $i->{Lin}";
+	next if $t eq $last;
+	push @byratnew, $i;
+	$last= $t;
+    }
+    @byrat= @byratnew;
+}
+
 sub byratcol ($$$) {
     my ($or,$cwr,$colnum) = @_;
     $$or .= '  ' if $colnum;
@@ -109,19 +156,21 @@ sub byratcol ($$$) {
 
 sub printbyrat () {
     use integer;
-    my ($brcols) = 8;
+    my ($brcols) = $three ? 19 : 8;
     my ($brrows) = (@byrat+$brcols-1) / $brcols;
     my ($byrat,$o,$colnum,$rownum,$cw);
     $o= ''; 
     for ($colnum=0; $colnum<$brcols; $colnum++) {
 	byratcol(\$o,\$cw,$colnum);
-	$o .= sprintf("N/D %".($cw+1)."s %s",
-		      'Q*10^k','fc(Lg)');
+	$o .= sprintf("N:D%s %".($cw+1)."s",
+		      $three ? '[&X]' : '',
+		      'Q*10^k');
+	$o .= sprintf(" %s", $three ? '' : 'fc(Lg)');
     }
     $o .= "\n";
     for ($colnum=0; $colnum<$brcols; $colnum++) {
 	byratcol(\$o,\$cw,$colnum);
-	$o .= '-' x (5+1+$cw+1+5);
+	$o .= '-' x (5+1+$cw+($three ? 4 : 1+5));
     }
     $o .= "\n";
     for ($rownum=0; $rownum<$brrows; $rownum++) { 
@@ -129,10 +178,10 @@ sub printbyrat () {
 	    $byrat= $byrat[$colnum*$brrows + $rownum];
 	    next unless defined $byrat;
 	    byratcol(\$o,\$cw,$colnum);
-	    $o .= sprintf("%2s/%-2s %${cw}s %s",
+	    $o .= sprintf("%2s:%-".($three ? 6 : 2)."s %${cw}s",
 			  $byrat->{Num}, $byrat->{Den},
-			  mul10fit($byrat->{Lin}, $cw),
-			  fracfit($byrat->{Log}, 5));
+			  mul10fit($byrat->{Lin}, $cw));
+	    $o .= sprintf(" %s", fracfit($byrat->{Log}, 5)) unless $three;
 	}
 	$o .= "\n";
     }
@@ -141,8 +190,11 @@ sub printbyrat () {
 
 print "\n" or die $!;
 scan();
-ptable($tlin);
-ptable($tlog);
+if (!$three) {
+    ptable($tlin);
+    ptable($tlog);
+}
 
 sortbyrat();
+uniqbyrat() if $three;
 printbyrat();