Add trunc(…) function

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).

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")

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);

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);