gallery+docs: Update gallery + manual

doc/style.typ

@@ -1,14 +1,14 @@
 #import "/src/lib.typ"
 
 #import "@preview/tidy:0.4.3"
-#import "@preview/t4t:0.3.2": is
+#import "@preview/t4t:0.3.2": is as is_
 
 #let show-function(fn, style-args) = {
   [
     #heading(fn.name, level: style-args.first-heading-level + 1)
     #label(style-args.label-prefix + fn.name + "()")
   ]
-  let description = if is.sequence(fn.description) {
+  let description = if is_.sequence(fn.description) {
     fn.description.children
   } else {
     (fn.description,)

gallery/normal-dist.typ

@@ -0,0 +1,58 @@
+#import "@preview/cetz:0.5.2": canvas, draw
+#import "@preview/cetz-plot:0.1.4": plot
+
+#set page(width: auto, height: auto, margin: .5cm)
+
+#let style = (stroke: black, fill: rgb(0, 0, 200, 75))
+
+#let f(x, rho: .4, sigma: 0) = 1 / calc.sqrt(2 * calc.pi * rho * rho) * calc.exp(-calc.pow(x - sigma, 2)/(2 * rho * rho))
+
+#set text(size: 10pt, fill: white)
+
+#canvas(background: gray.darken(80%), {
+  import draw: *
+
+  set-style(
+    axes: (
+      stroke: 1pt + white,
+      tick: (stroke: 1pt + white),
+      fill: gray.darken(60%),
+      minor-tick: (stroke: white),
+      grid: (stroke: (thickness: .5pt, paint: white, dash: "dotted")),
+    ),
+    legend: (
+      fill: black.transparentize(60%),
+      stroke: none,
+      padding: .3cm,
+      offset: (-.1, -.1)
+    )
+  )
+
+  let x-format = x => {
+    if x > 0 { $mu + #{x}sigma$ }
+    else if x < 0 { $mu - #{calc.abs(x)}sigma$ }
+    else { $mu$ }
+  }
+
+  plot.plot(size: (12, 8),
+    x-tick-step: 1,
+    y-tick-step: 1,
+    x-format: x-format,
+    y-max: 1.1,
+    y-min: -.1,
+    x-grid: true,
+    y-grid: true,
+    x-label: none,
+    y-label: none,
+    legend: "inner-north-east",
+    {
+      plot.add(f, domain: (-3, +3),
+        style: (stroke: green),
+        label: $y = 1/sqrt(2 pi sigma^2) exp(-(x - mu)^2/(2 sigma^2)) $,
+        samples: 200,
+      )
+    })
+
+  // Add some padding
+  rect((-1, -1), (13, 9))
+})