Update fibonacci example and add round function

README.md

@@ -37,7 +37,7 @@ A [gentle introduction][tutorial] to Typst is available in our documentation.
 However, if you want to see the power of Typst encapsulated in one image, here
 it is:
 <p align="center">
- <img alt="Example" width="900" src="https://user-images.githubusercontent.com/38260698/226794868-90911832-433a-4575-be88-42d582589403.png"/>
+ <img alt="Example" width="900" src="https://user-images.githubusercontent.com/17899797/228031796-ced0e452-fcee-4ae9-92da-b9287764ff25.png"/>
 </p>
 
 
@@ -78,13 +78,13 @@ Let's dissect what's going on:
 
   = Fibonacci sequence
   The Fibonacci sequence is defined through the
-  _recurrence relation_ $F_n = F_(n-1) + F_(n-2)$.
+  recurrence relation $F_n = F_(n-1) + F_(n-2)$.
-  It can also be expressed in closed form:
+  It can also be expressed in _closed form:_
 
-  $ F_n = floor(1 / sqrt(5) phi.alt^n), quad
+  $ F_n = round(1 / sqrt(5) phi.alt^n), quad
     phi.alt = (1 + sqrt(5)) / 2 $
 
-  #let count = 10
+  #let count = 8
   #let nums = range(1, count + 1)
   #let fib(n) = (
     if n <= 2 { 1 }

docs/src/general/changelog.md

@@ -18,11 +18,12 @@ description: |
 - Fixed [matrices]($func/mat) with explicit delimiter
 - Fixed build of CLI if `git` is not installed
 - Links in bibliographies are now affected by link styling
-  `[#counter(..).update(0)]`
 - Added support for disabling [matrix]($func/mat) and [vector]($func/vec)
   delimiters. Generally with `[#set math.mat(delim: none)]` or one-off with
   `[$mat(delim: #none, 1, 2; 3, 4)$]`.
+- Added [`round`]($func/round) function for equations
 - Numberings now allow zeros. To reset a counter, you can write
+  `[#counter(..).update(0)]`
 - Added `--font-path` argument for CLI
 - Added Nix flake
 - Numerous documentation fixes

library/src/math/delimited.rs

@@ -141,6 +141,24 @@ pub fn ceil(
     delimited(body, '⌈', '⌉')
 }
 
+/// Round an expression.
+///
+/// ## Example
+/// ```example
+/// $ round(x/2) $
+/// ```
+///
+/// Display: Round
+/// Category: math
+/// Returns: content
+#[func]
+pub fn round(
+    /// The expression to round.
+    body: Content,
+) -> Value {
+    delimited(body, '⌊', '⌉')
+}
+
 /// Take the absolute value of an expression.
 ///
 /// ## Example

library/src/math/mod.rs

@@ -57,6 +57,7 @@ pub fn module() -> Module {
     math.define("norm", norm);
     math.define("floor", floor);
     math.define("ceil", ceil);
+    math.define("round", round);
 
     // Attachments and accents.
     math.define("attach", AttachElem::func());

tests/typ/math/numbering.typ

@@ -8,4 +8,4 @@ We define $x$ in preparation of @fib:
 $ phi.alt := (1 + sqrt(5)) / 2 $ <ratio>
 
 With @ratio, we get
-$ F_n = floor(1 / sqrt(5) phi.alt^n) $ <fib>
+$ F_n = round(1 / sqrt(5) phi.alt^n) $ <fib>