From 4e0d5451854d8d3ad199afbb5824bb01d4a6a40e Mon Sep 17 00:00:00 2001
From: David Peter <mail@david-peter.de>
Date: Wed, 24 Jul 2024 19:23:01 +0200
Subject: [PATCH] =?UTF-8?q?Add=20trunc(=E2=80=A6)=20function?=
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---
 book/src/list-functions-math.md   | 8 ++++++++
 numbat/modules/core/functions.nbt | 5 +++++
 numbat/src/ffi/functions.rs       | 1 +
 numbat/src/ffi/math.rs            | 1 +
 4 files changed, 15 insertions(+)

diff --git a/book/src/list-functions-math.md b/book/src/list-functions-math.md
index 7b191d90..f39aa5bc 100644
--- a/book/src/list-functions-math.md
+++ b/book/src/list-functions-math.md
@@ -68,6 +68,14 @@ More information [here](https://doc.rust-lang.org/std/primitive.f64.html#method.
 fn ceil<T: Dim>(x: T) -> T
 ```
 
+### `trunc` (Truncation)
+Returns the integer part of \\( x \\). Non-integer numbers are always truncated towards zero.
+More information [here](https://doc.rust-lang.org/std/primitive.f64.html#method.trunc).
+
+```nbt
+fn trunc<T: Dim>(x: T) -> T
+```
+
 ### `mod` (Modulo)
 Calculates the least nonnegative remainder of \\( a (\mod b) \\).
 More information [here](https://doc.rust-lang.org/std/primitive.f64.html#method.rem_euclid).
diff --git a/numbat/modules/core/functions.nbt b/numbat/modules/core/functions.nbt
index 8211bda4..c42b74cf 100644
--- a/numbat/modules/core/functions.nbt
+++ b/numbat/modules/core/functions.nbt
@@ -36,6 +36,11 @@ fn floor<T: Dim>(x: T) -> T
 @url("https://doc.rust-lang.org/std/primitive.f64.html#method.ceil")
 fn ceil<T: Dim>(x: T) -> T
 
+@name("Truncation")
+@description("Returns the integer part of $x$. Non-integer numbers are always truncated towards zero.")
+@url("https://doc.rust-lang.org/std/primitive.f64.html#method.trunc")
+fn trunc<T: Dim>(x: T) -> T
+
 @name("Modulo")
 @description("Calculates the least nonnegative remainder of $a (\\mod b)$.")
 @url("https://doc.rust-lang.org/std/primitive.f64.html#method.rem_euclid")
diff --git a/numbat/src/ffi/functions.rs b/numbat/src/ffi/functions.rs
index 87ea5e6d..f7bae256 100644
--- a/numbat/src/ffi/functions.rs
+++ b/numbat/src/ffi/functions.rs
@@ -46,6 +46,7 @@ pub(crate) fn functions() -> &'static HashMap<String, ForeignFunction> {
         insert_function!(round, 1..=1);
         insert_function!(floor, 1..=1);
         insert_function!(ceil, 1..=1);
+        insert_function!(trunc, 1..=1);
 
         insert_function!(sin, 1..=1);
         insert_function!(cos, 1..=1);
diff --git a/numbat/src/ffi/math.rs b/numbat/src/ffi/math.rs
index 3fdb23d1..b90e556e 100644
--- a/numbat/src/ffi/math.rs
+++ b/numbat/src/ffi/math.rs
@@ -41,6 +41,7 @@ simple_polymorphic_math_function!(abs, abs);
 simple_polymorphic_math_function!(round, round);
 simple_polymorphic_math_function!(floor, floor);
 simple_polymorphic_math_function!(ceil, ceil);
+simple_polymorphic_math_function!(trunc, trunc);
 
 simple_scalar_math_function!(sin, sin);
 simple_scalar_math_function!(cos, cos);