Add norm_{l1,l2,max} in Vector crate

Author: termoshtt

src/vector.rs

@@ -1,18 +1,57 @@
 //! Define trait for vectors
 
-use ndarray::{LinalgScalar, Array, Ix1};
+use std::iter::Sum;
+use ndarray::{LinalgScalar, ArrayBase, Data, Dimension};
 use num_traits::float::Float;
 
 /// Methods for vectors
 pub trait Vector {
     type Scalar;
+    /// rename of norm_l2
+    fn norm(&self) -> Self::Scalar {
+        self.norm_l2()
+    }
+    /// L-1 norm
+    fn norm_l1(&self) -> Self::Scalar;
     /// L-2 norm
-    fn norm(&self) -> Self::Scalar;
+    fn norm_l2(&self) -> Self::Scalar;
+    /// maximum norm
+    fn norm_max(&self) -> Self::Scalar;
 }
 
-impl<A: Float + LinalgScalar> Vector for Array<A, Ix1> {
-    type Scalar = A;
-    fn norm(&self) -> Self::Scalar {
-        self.dot(&self).sqrt()
+impl<A, S, D, T> Vector for ArrayBase<S, D>
+    where A: LinalgScalar + Squared<Output = T>,
+          T: Float + Sum,
+          S: Data<Elem = A>,
+          D: Dimension
+{
+    type Scalar = T;
+    fn norm_l1(&self) -> Self::Scalar {
+        self.iter().map(|x| x.sq_abs()).sum()
+    }
+    fn norm_l2(&self) -> Self::Scalar {
+        self.iter().map(|x| x.squared()).sum::<T>().sqrt()
+    }
+    fn norm_max(&self) -> Self::Scalar {
+        self.iter().fold(T::zero(), |f, &val| {
+            let v = val.sq_abs();
+            if f > v { f } else { v }
+        })
+    }
+}
+
+pub trait Squared {
+    type Output;
+    fn squared(&self) -> Self::Output;
+    fn sq_abs(&self) -> Self::Output;
+}
+
+impl<A: Float> Squared for A {
+    type Output = A;
+    fn squared(&self) -> A {
+        *self * *self
+    }
+    fn sq_abs(&self) -> A {
+        self.abs()
     }
 }