Add vertical kern to \vdots (#1402)

* Add vertical kern to \vdots

Fixes #620.

* Replaced screenshots

src/macros.js

@@ -238,6 +238,16 @@ defineMacro("\u27C2", "\\perp");
 defineMacro("\u203C", "\\mathclose{!\\mkern-0.8mu!}");
 defineMacro("\u220C", "\\notni");
 
+//////////////////////////////////////////////////////////////////////
+// LaTeX_2ε
+
+// \vdots{\vbox{\baselineskip4\p@  \lineskiplimit\z@
+// \kern6\p@\hbox{.}\hbox{.}\hbox{.}}}
+// We'll call \varvdots, which gets a glyph from symbols.js.
+// The zero-width rule gets us an equivalent to the vertical 6pt kern.
+defineMacro("\\vdots", "\\mathord{\\varvdots\\rule{0pt}{15pt}}");
+defineMacro("\u22ee", "\\vdots");
+
 //////////////////////////////////////////////////////////////////////
 // amsmath.sty
 // http://mirrors.concertpass.com/tex-archive/macros/latex/required/amsmath/amsmath.pdf

src/symbols.js

@@ -655,7 +655,7 @@ defineSymbol(text, main, inner, "\u2026", "\\ldots", true);
 defineSymbol(math, main, inner, "\u2026", "\\ldots", true);
 defineSymbol(math, main, inner, "\u22ef", "\\@cdots", true);
 defineSymbol(math, main, inner, "\u22f1", "\\ddots", true);
-defineSymbol(math, main, textord, "\u22ee", "\\vdots", true);
+defineSymbol(math, main, textord, "\u22ee", "\\varvdots"); // \vdots is a macro
 defineSymbol(math, main, accent, "\u02ca", "\\acute");
 defineSymbol(math, main, accent, "\u02cb", "\\grave");
 defineSymbol(math, main, accent, "\u00a8", "\\ddot");

test/katex-spec.js

@@ -2893,7 +2893,7 @@ describe("Unicode", function() {
     });
 
     it("should parse symbols", function() {
-        expect("£¥ðℂℍℑℓℕ℘ℙℚℜℝℤℲℵℶℷℸ⅁∀∁∂∃∇∞∠∡∢♠♡♢♣♭♮♯✓°¬‼\u00b7").toParse(strictSettings);
+        expect("£¥ðℂℍℑℓℕ℘ℙℚℜℝℤℲℵℶℷℸ⅁∀∁∂∃∇∞∠∡∢♠♡♢♣♭♮♯✓°¬‼⋮\u00b7").toParse(strictSettings);
     });
 
     it("should build Greek capital letters", function() {