Fix compilation when targetting no-std.

src/geometry/dual_quaternion.rs

@@ -1,6 +1,6 @@
 use crate::{
     Isometry3, Matrix4, Normed, Point3, Quaternion, Scalar, SimdRealField, Translation3, Unit,
-    UnitQuaternion, Vector3, VectorN, U8,
+    UnitQuaternion, Vector3, VectorN, Zero, U8,
 };
 use approx::{AbsDiffEq, RelativeEq, UlpsEq};
 #[cfg(feature = "serde-serialize")]
@@ -35,14 +35,23 @@ use simba::scalar::{ClosedNeg, RealField};
 ///  If a feature that you need is missing, feel free to open an issue or a PR.
 ///  See https://github.com/dimforge/nalgebra/issues/487
 #[repr(C)]
-#[derive(Debug, Default, Eq, PartialEq, Copy, Clone)]
-pub struct DualQuaternion<N: SimdRealField> {
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+pub struct DualQuaternion<N: Scalar> {
     /// The real component of the quaternion
     pub real: Quaternion<N>,
     /// The dual component of the quaternion
     pub dual: Quaternion<N>,
 }
 
+impl<N: Scalar + Zero> Default for DualQuaternion<N> {
+    fn default() -> Self {
+        Self {
+            real: Quaternion::default(),
+            dual: Quaternion::default(),
+        }
+    }
+}
+
 impl<N: SimdRealField> DualQuaternion<N>
 where
     N::Element: SimdRealField,

src/geometry/dual_quaternion_construction.rs

@@ -1,12 +1,12 @@
 use crate::{
-    DualQuaternion, Isometry3, Quaternion, SimdRealField, Translation3, UnitDualQuaternion,
+    DualQuaternion, Isometry3, Quaternion, Scalar, SimdRealField, Translation3, UnitDualQuaternion,
     UnitQuaternion,
 };
 use num::{One, Zero};
 #[cfg(feature = "arbitrary")]
 use quickcheck::{Arbitrary, Gen};
 
-impl<N: SimdRealField> DualQuaternion<N> {
+impl<N: Scalar> DualQuaternion<N> {
     /// Creates a dual quaternion from its rotation and translation components.
     ///
     /// # Example
@@ -40,7 +40,10 @@ impl<N: SimdRealField> DualQuaternion<N> {
     /// assert_eq!(dq2 * dq1, dq2);
     /// ```
     #[inline]
-    pub fn identity() -> Self {
+    pub fn identity() -> Self
+    where
+        N: SimdRealField,
+    {
         Self::from_real_and_dual(
             Quaternion::from_real(N::one()),
             Quaternion::from_real(N::zero()),