round displacement when converting units

1 files changed, 16 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index cd3320a..c41b791 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,19 @@
 pub mod volume;
 
 type Percent = u8;
+
+pub fn round<F, I>(f: F, digits: I) -> f64
+where
+    F: Into<f64>,
+    I: Into<i32> + Copy,
+{
+    (f.into() * 10_f64.powi(digits.into())).round() / 10_f64.powi(digits.into())
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn round() {
+        assert_eq!(super::round(0.123456789, 3), 0.123);
+    }
+}