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Library/mrmugame/Silverbullet-Math.md

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+---
+name: Library/mrmugame/Silverbullet-Math
+tags: meta/library
+files:
+  - Silverbullet-Math/katex.mjs
+  - Silverbullet-Math/katex.min.css
+  - Silverbullet-Math/fonts/KaTeX_Typewriter-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Size4-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Size3-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Size2-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Size1-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Script-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_SansSerif-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_SansSerif-Italic.woff2
+  - Silverbullet-Math/fonts/KaTeX_SansSerif-Bold.woff2
+  - Silverbullet-Math/fonts/KaTeX_Math-Italic.woff2
+  - Silverbullet-Math/fonts/KaTeX_Math-BoldItalic.woff2
+  - Silverbullet-Math/fonts/KaTeX_Main-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Main-Italic.woff2
+  - Silverbullet-Math/fonts/KaTeX_Main-Bold.woff2
+  - Silverbullet-Math/fonts/KaTeX_Main-BoldItalic.woff2
+  - Silverbullet-Math/fonts/KaTeX_Fraktur-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Fraktur-Bold.woff2
+  - Silverbullet-Math/fonts/KaTeX_Caligraphic-Regular.woff2
+  - Silverbullet-Math/fonts/KaTeX_Caligraphic-Bold.woff2
+  - Silverbullet-Math/fonts/KaTeX_AMS-Regular.woff2
+share.uri: "https://github.com/MrMugame/silverbullet-math/blob/main/Math.md"
+share.hash: "13247895"
+share.mode: pull
+---
+
+# Silverbullet Math
+This library implements two new widgets
+
+- `latex.block(...)` and
+- `latex.inline(...)`,
+
+which can be used to render block and inline level math respectively. Both use ${latex.inline[[\href{https://katex.org/}{\KaTeX}]]} under the hood
+
+## Examples
+Let ${latex.inline[[S]]} be a set and ${latex.inline[[\circ : S \times S \to S,\; (a, b) \mapsto a \cdot b]]} be a binary operation, then the pair ${latex.inline[[(S, \circ)]]} is called a *group* iff
+
+1. ${latex.inline[[\forall a, b \in S, \; a \circ b \in S]]} (completeness),
+2. ${latex.inline[[\forall a,b,c \in S, \; (ab)c = a(bc)]]} (associativity),
+3. ${latex.inline[[\exists e \in S]]} such that ${latex.inline[[\forall a \in S,\; ae=a=ea]]} (identity) and
+4. ${latex.inline[[\forall a \in S,\; \exists b \in S]]} such that ${latex.inline[[ab=e=ba]]} (inverse).
+
+The Fourier transform of a complex-valued (Lebesgue) integrable function ${latex.inline[[f(x)]]} on the real line, is the complex valued function ${latex.inline[[\hat {f}(\xi )]]}, defined by the integral
+${latex.block[[\widehat{f}(\xi) = \int_{-\infty}^{\infty} f(x)\ e^{-i 2\pi \xi x}\,dx, \quad \forall \xi \in \mathbb{R}.]]}
+
+## Quality of life
+There are two slash commands to make writing math a little easier,
+
+- `/math` and
+- `/equation`.
+
+## Info
+The current ${latex.inline[[\KaTeX]]} version is ${latex.katex.version}.
+
+## Implementation
+```space-lua
+local location = "Library/mrmugame/Silverbullet-Math"
+
+-- TODO: Remove the check for system.getURLPrefix as soon as the API has settled
+latex = {
+  header = string.format("<link rel=\"stylesheet\" href=\".fs/%s/katex.min.css\">", location),
+  katex = js.import(string.format("%s.fs/%s/katex.mjs", system.getURLPrefix and system.getURLPrefix() or "/",  location))
+}
+
+function latex.inline(expression)
+  local html = latex.katex.renderToString(expression, {
+    trust = true,
+    throwOnError = false,
+    displayMode = false
+  })
+
+  return widget.new {
+    display = "inline",
+    html = "<span>" .. latex.header .. html .. "</span>"
+  }
+end
+
+function latex.block(expression)
+  local html = latex.katex.renderToString(expression, {
+    trust = true,
+    throwOnError = false,
+    displayMode = true
+  })
+
+  return widget.new {
+    display = "block",
+    html = "<span>" .. latex.header .. html .. "</span>"
+  }
+end
+
+slashcommand.define {
+  name = "math",
+  run = function()
+    editor.insertAtCursor("${latex.inline[[]]}", false, true)
+    editor.moveCursor(editor.getCursor() - 3)
+  end
+}
+
+slashcommand.define {
+  name = "equation",
+  run = function()
+    editor.insertAtCursor("${latex.block[[]]}", false, true)
+    editor.moveCursor(editor.getCursor() - 3)
+  end
+}
+```
+
+```space-style
+.sb-lua-directive-inline:has(.katex-html) {
+  border: none !important;
+}
+```