From 62829dc9d34a84f892a0b5c5829faebf89c787f3 Mon Sep 17 00:00:00 2001
From: Robin Munn <rmunn@pobox.com>
Date: Mon, 17 Jun 2019 12:34:30 -0500
Subject: [PATCH] Add untrunc operator, the mirror of trunc (#3994)

---
 core/modules/filters/math.js                      |  4 ++++
 editions/prerelease/tiddlers/Release 5.1.20.tid   |  2 +-
 .../examples/untrunc Operator (Examples).tid      |  9 +++++++++
 .../tw5.com/tiddlers/filters/trunc Operator.tid   |  2 ++
 .../tw5.com/tiddlers/filters/untrunc Operator.tid | 15 +++++++++++++++
 5 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 editions/tw5.com/tiddlers/filters/examples/untrunc Operator (Examples).tid
 create mode 100644 editions/tw5.com/tiddlers/filters/untrunc Operator.tid

diff --git a/core/modules/filters/math.js b/core/modules/filters/math.js
index 801ebf5ed..c3f6d3b45 100644
--- a/core/modules/filters/math.js
+++ b/core/modules/filters/math.js
@@ -43,6 +43,10 @@ exports.trunc = makeNumericBinaryOperator(
 	function(a) {return Math.trunc(a)}
 );
 
+exports.untrunc = makeNumericBinaryOperator(
+	function(a) {return Math.ceil(Math.abs(a)) * Math.sign(a)}
+);
+
 exports.sign = makeNumericBinaryOperator(
 	function(a) {return Math.sign(a)}
 );
diff --git a/editions/prerelease/tiddlers/Release 5.1.20.tid b/editions/prerelease/tiddlers/Release 5.1.20.tid
index 47baa720a..aac0e9259 100644
--- a/editions/prerelease/tiddlers/Release 5.1.20.tid	
+++ b/editions/prerelease/tiddlers/Release 5.1.20.tid	
@@ -9,7 +9,7 @@ type: text/vnd.tiddlywiki
 
 !! Major Improvements
 
-Added several new [[Mathematics Operators]] for working with numbers: [[negate|negate Operator]], [[abs|abs Operator]], [[ceil|ceil Operator]], [[floor|floor Operator]], [[round|round Operator]], [[trunc|trunc Operator]], [[sign|sign Operator]], [[add|add Operator]], [[subtract|subtract Operator]], [[multiply|multiply Operator]], [[divide|divide Operator]], [[remainder|remainder Operator]], [[max|max Operator]], [[min|min Operator]], [[fixed|fixed Operator]], [[precision|precision Operator]], [[exponential|exponential Operator]], [[sum|sum Operator]], [[product|product Operator]], [[maxall|maxall Operator]] and [[minall|minall Operator]].
+Added several new [[Mathematics Operators]] for working with numbers: [[negate|negate Operator]], [[abs|abs Operator]], [[ceil|ceil Operator]], [[floor|floor Operator]], [[round|round Operator]], [[trunc|trunc Operator]], [[untrunc|untrunc Operator]], [[sign|sign Operator]], [[add|add Operator]], [[subtract|subtract Operator]], [[multiply|multiply Operator]], [[divide|divide Operator]], [[remainder|remainder Operator]], [[max|max Operator]], [[min|min Operator]], [[fixed|fixed Operator]], [[precision|precision Operator]], [[exponential|exponential Operator]], [[sum|sum Operator]], [[product|product Operator]], [[maxall|maxall Operator]] and [[minall|minall Operator]].
 
 Added several new string operators: [[length|length Operator]], [[uppercase|uppercase Operator]], [[lowercase|lowercase Operator]], [[trim|trim Operator]], [[split|split Operator]], [[splitregexp|split Operator]] and [[join|join Operator]].
 
diff --git a/editions/tw5.com/tiddlers/filters/examples/untrunc Operator (Examples).tid b/editions/tw5.com/tiddlers/filters/examples/untrunc Operator (Examples).tid
new file mode 100644
index 000000000..a1415001a
--- /dev/null
+++ b/editions/tw5.com/tiddlers/filters/examples/untrunc Operator (Examples).tid	
@@ -0,0 +1,9 @@
+created: 20190617162921280
+modified: 20190617162921280
+tags: [[untrunc Operator]] [[Operator Examples]]
+title: untrunc Operator (Examples)
+type: text/vnd.tiddlywiki
+
+<<.operator-example 1 "[[1.6]untrunc[]]">>
+<<.operator-example 2 "[[-1.6]untrunc[]]">>
+<<.operator-example 3 "=-1.2 =-2.4 =3.6 =4.8 =5.1 +[untrunc[]]">>
diff --git a/editions/tw5.com/tiddlers/filters/trunc Operator.tid b/editions/tw5.com/tiddlers/filters/trunc Operator.tid
index 43cf2d2dd..72bb23534 100644
--- a/editions/tw5.com/tiddlers/filters/trunc Operator.tid	
+++ b/editions/tw5.com/tiddlers/filters/trunc Operator.tid	
@@ -10,4 +10,6 @@ type: text/vnd.tiddlywiki
 
 <<.from-version "5.1.20">> See [[Mathematics Operators]] for an overview.
 
+<<.tip " The trunc operator rounds towards zero. To round away from zero, use [[untrunc|untrunc Operator]].">>
+
 <<.operator-examples "trunc">>
diff --git a/editions/tw5.com/tiddlers/filters/untrunc Operator.tid b/editions/tw5.com/tiddlers/filters/untrunc Operator.tid
new file mode 100644
index 000000000..9aaf06295
--- /dev/null
+++ b/editions/tw5.com/tiddlers/filters/untrunc Operator.tid	
@@ -0,0 +1,15 @@
+caption: untrunc
+created: 20190617163327756
+modified: 20190617163327756
+op-input: a [[selection of titles|Title Selection]]
+op-output: rounds each of the input numbers to the next integer with largest absolute value, that is, away from zero
+op-purpose: rounds a list of numbers to the next integer with largest absolute value, that is, away from zero
+tags: [[Unary Mathematics Operators]] [[Filter Operators]] [[Mathematics Operators]]
+title: untrunc Operator
+type: text/vnd.tiddlywiki
+
+<<.from-version "5.1.20">> See [[Mathematics Operators]] for an overview.
+
+<<.tip " This is the inverse operation of [[trunc|trunc Operator]]: trunc rounds to zero, but untrunc rounds away from zero.">>
+
+<<.operator-examples "untrunc">>