Add delta-transformation.

src/traits/delta_transform.rs

@@ -0,0 +1,10 @@
+/// A delta-transformation is the generalization of rotation. A delta transform
+/// can apply any transformation to the object without translating it.
+/// In partilular, 0 is neutral wrt. the delta-transform.
+pub trait DeltaTransform<DT>
+{
+  /// Extracts the delta transformation associated with this transformation.
+  fn delta_transform(&self) -> DT;
+  // FIXME: add functions to apply the delta-transform to a vector without
+  // explicit computation of the transform (does this avoid some matrix copy?)
+}

src/traits/division_ring.rs

@@ -0,0 +1,4 @@
+use traits::ring::Ring;
+
+pub trait DivisionRing : Ring + Quot<Self, Self>
+{ }

src/traits/ring.rs

@@ -0,0 +1,5 @@
+use core::num::{One, Zero};
+
+pub trait Ring :
+Sub<Self, Self> + Add<Self, Self> + Neg<Self> + Mul<Self, Self> + One + Zero
+{ }

src/traits/vector_space.rs

@@ -0,0 +1,7 @@
+use core::num::Zero;
+use traits::division_ring::DivisionRing;
+use traits::workarounds::scalar_op::{ScalarMul, ScalarDiv};
+
+pub trait VectorSpace<T: DivisionRing> : Sub<Self, Self> + Add<Self, Self> +
+                                         Neg<Self> + Zero + ScalarMul<T> + ScalarDiv<T>
+{ }