Add bra-ket notation (#2162)

* Add bra-ket notation

* Fix typo

* Remove ketbra

* Remove ketbra, add Bra and Ket

* Add Bra/Ket and fix a typo in bra's source

* Fix bra-ket typo in docs

* Fix bra-ket escape typo in docs

* Replace bra-ket pipe with \vert in docs

docs/support_table.md

@@ -183,6 +183,9 @@ table td {
 |\boxminus|$\boxminus$||
 |\boxplus|$\boxplus$||
 |\boxtimes|$\boxtimes$||
+|\Bra|$\left\langle\psi\right\|$|`\Bra{\psi}`|
+|\bra|$\mathinner{\langle{\psi}\|}$|`\bra{\psi}`|
+|\braket|$\mathinner{\langle{\phi\|\psi}\rangle}$|`\braket{\phi|\psi}`|
 |\brace|${n\brace k}$|`{n\brace k}`|
 |\bracevert|<span style="color:firebrick;">Not supported</span>||
 |\brack|${n\brack k}$|`{n\brack k}`|
@@ -511,6 +514,8 @@ use `\ce` instead|
 |\KaTeX|$\KaTeX$||
 |\ker|$\ker$||
 |\kern|$I\kern-2.5pt R$|`I\kern-2.5pt R`|
+|\Ket|$\left\|\psi\right\rangle$|`\Ket{\psi}`|
+|\ket|$\mathinner{\|{\psi}\rangle}$|`\ket{\psi}`|
 |\Koppa|<span style="color:firebrick;">Not supported</span>||
 |\koppa|<span style="color:firebrick;">Not supported</span>||
 

docs/supported.md

@@ -510,6 +510,15 @@ Direct Input: $← ↑ → ↓ ↔ ↕ ↖ ↗ ↘ ↙ ↚ ↛ ↞ ↠ ↢ ↣
 
 Extensible arrows all can take an optional argument in the same manner<br>as `\xrightarrow[under]{over}`.
 
+## Special Notation
+
+**Bra-ket Notation**
+
+||||
+|:----------|:----------|:----------|
+|$\bra{\phi}$ `\bra{\phi}` |$\ket{\psi}$ `\ket{\psi}` |$\braket{\phi\vert\psi}$ `\braket{\phi\vert\psi}` |
+|$\Bra{\phi}$ `\Bra{\phi}` |$\Ket{\psi}$ `\Ket{\psi}` ||
+
 ## Style, Color, Size, and Font
 
 **Class Assignment**

src/macros.js

@@ -930,6 +930,16 @@ defineMacro("\\argmin", "\\DOTSB\\operatorname*{arg\\,min}");
 defineMacro("\\argmax", "\\DOTSB\\operatorname*{arg\\,max}");
 defineMacro("\\plim", "\\DOTSB\\mathop{\\operatorname{plim}}\\limits");
 
+//////////////////////////////////////////////////////////////////////
+// braket.sty
+// http://ctan.math.washington.edu/tex-archive/macros/latex/contrib/braket/braket.pdf
+
+defineMacro("\\bra", "\\mathinner{\\langle{#1}|}");
+defineMacro("\\ket", "\\mathinner{|{#1}\\rangle}");
+defineMacro("\\braket", "\\mathinner{\\langle{#1}\\rangle}");
+defineMacro("\\Bra", "\\left\\langle#1\\right|");
+defineMacro("\\Ket", "\\left|#1\\right\\rangle");
+
 // Custom Khan Academy colors, should be moved to an optional package
 defineMacro("\\blue", "\\textcolor{##6495ed}{#1}");
 defineMacro("\\orange", "\\textcolor{##ffa500}{#1}");

test/katex-spec.js

@@ -3312,6 +3312,26 @@ describe("A macro expander", function() {
     it("should expand \\argmax as expected", () => {
         expect`\argmax`.toParseLike`\operatorname*{arg\,max}`;
     });
+
+    it("should expand \\bra as expected", () => {
+        expect`\bra{\phi}`.toParseLike`\mathinner{\langle{\phi}|}`;
+    });
+
+    it("should expand \\ket as expected", () => {
+        expect`\ket{\psi}`.toParseLike`\mathinner{|{\psi}\rangle}`;
+    });
+
+    it("should expand \\braket as expected", () => {
+        expect`\braket{\phi|\psi}`.toParseLike`\mathinner{\langle{\phi|\psi}\rangle}`;
+    });
+
+    it("should expand \\Bra as expected", () => {
+        expect`\Bra{\phi}`.toParseLike`\left\langle\phi\right|`;
+    });
+
+    it("should expand \\Ket as expected", () => {
+        expect`\Ket{\psi}`.toParseLike`\left|\psi\right\rangle`;
+    });
 });
 
 describe("\\tag support", function() {