Adding matmul?

src/storage.rs

@@ -241,4 +241,22 @@ impl Storage {
     pub(crate) fn sqrt_impl(&self, shape: &Shape, stride: &[usize]) -> Result<Self> {
         self.unary_impl::<Sqrt>(shape, stride)
     }
+
+    pub(crate) fn matmul_impl(
+        &self,
+        rhs: &Self,
+        bmnk: (usize, usize, usize, usize),
+        lhs_stride: &[usize],
+        rhs_stride: &[usize],
+    ) -> Result<Self> {
+        self.same_device(rhs, "matmul")?;
+        self.same_dtype(rhs, "matmul")?;
+        match (self, rhs) {
+            (Storage::Cpu(storage), Storage::Cpu(rhs_storage)) => {
+                let storage = storage.matmul_impl(rhs_storage, bmnk, lhs_stride, rhs_stride)?;
+                Ok(Self::Cpu(storage))
+            }
+            _ => todo!(),
+        }
+    }
 }