Merge pull request #148 from rust-ndarray/inner_prod

Inner Product

Author: termoshtt

src/inner.rs

@@ -0,0 +1,30 @@
+use crate::types::*;
+use ndarray::*;
+
+/// Inner Product
+///
+/// Differenct from `Dot` trait, this take complex conjugate of `self` elements
+///
+pub trait InnerProduct {
+    type Elem: Scalar;
+
+    /// Inner product `(self.conjugate, rhs)
+    fn inner<S>(&self, rhs: &ArrayBase<S, Ix1>) -> Self::Elem
+    where
+        S: Data<Elem = Self::Elem>;
+}
+
+impl<A, S> InnerProduct for ArrayBase<S, Ix1>
+where
+    A: Scalar,
+    S: Data<Elem = A>,
+{
+    type Elem = A;
+    fn inner<St: Data<Elem = A>>(&self, rhs: &ArrayBase<St, Ix1>) -> A {
+        assert_eq!(self.len(), rhs.len());
+        Zip::from(self)
+            .and(rhs)
+            .fold_while(A::zero(), |acc, s, r| FoldWhile::Continue(acc + s.conj() * *r))
+            .into_inner()
+    }
+}

src/lib.rs

@@ -43,6 +43,7 @@ pub mod diagonal;
 pub mod eigh;
 pub mod error;
 pub mod generate;
+pub mod inner;
 pub mod lapack;
 pub mod layout;
 pub mod norm;
@@ -62,6 +63,7 @@ pub use convert::*;
 pub use diagonal::*;
 pub use eigh::*;
 pub use generate::*;
+pub use inner::*;
 pub use layout::*;
 pub use norm::*;
 pub use operator::*;

tests/inner.rs

@@ -0,0 +1,26 @@
+use ndarray::*;
+use ndarray_linalg::*;
+
+#[should_panic]
+#[test]
+fn size_shoter() {
+    let a: Array1<f32> = Array::zeros(3);
+    let b = Array::zeros(4);
+    a.inner(&b);
+}
+
+#[should_panic]
+#[test]
+fn size_longer() {
+    let a: Array1<f32> = Array::zeros(3);
+    let b = Array::zeros(4);
+    b.inner(&a);
+}
+
+#[test]
+fn abs() {
+    let a: Array1<c32> = random(1);
+    let aa = a.inner(&a);
+    assert_aclose!(aa.re(), a.norm().powi(2), 1e-5);
+    assert_aclose!(aa.im(), 0.0, 1e-5);
+}