Add inner product

Author: termoshtt

src/inner.rs

@@ -0,0 +1,21 @@
+use crate::types::*;
+use ndarray::*;
+
+pub trait Inner<S: Data> {
+    /// Inner product `(self.conjugate, rhs)`
+    fn inner(&self, rhs: &ArrayBase<S, Ix1>) -> S::Elem;
+}
+
+impl<A, S1, S2> Inner<S1> for ArrayBase<S2, Ix1>
+where
+    A: Scalar,
+    S1: Data<Elem = A>,
+    S2: Data<Elem = A>,
+{
+    fn inner(&self, rhs: &ArrayBase<S1, Ix1>) -> A {
+        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;