Add zip_apply and zip_zip_apply.

src/base/matrix.rs

@@ -706,8 +706,7 @@ impl<N: Scalar, R: Dim, C: Dim, S: StorageMut<N, R, C>> Matrix<N, R, C, S> {
 
     /// Replaces each component of `self` by the result of a closure `f` applied on it.
     #[inline]
-    pub fn apply<F: FnMut(N) -> N>(&mut self, mut f: F)
-    where DefaultAllocator: Allocator<N, R, C> {
+    pub fn apply<F: FnMut(N) -> N>(&mut self, mut f: F) {
         let (nrows, ncols) = self.shape();
 
         for j in 0..ncols {
@@ -719,6 +718,71 @@ impl<N: Scalar, R: Dim, C: Dim, S: StorageMut<N, R, C>> Matrix<N, R, C, S> {
             }
         }
     }
+
+    /// Replaces each component of `self` by the result of a closure `f` applied on its components
+    /// joined with the components from `rhs`.
+    #[inline]
+    pub fn zip_apply<N2, R2, C2, S2>(&mut self, rhs: Matrix<N2, R2, C2, S2>, mut f: impl FnMut(N, N2) -> N)
+        where N2: Scalar,
+              R2: Dim,
+              C2: Dim,
+              S2: Storage<N2, R2, C2>,
+              ShapeConstraint: SameNumberOfRows<R, R2> + SameNumberOfColumns<C, C2> {
+        let (nrows, ncols) = self.shape();
+
+        assert!(
+            (nrows, ncols) == rhs.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+
+        for j in 0..ncols {
+            for i in 0..nrows {
+                unsafe {
+                    let e = self.data.get_unchecked_mut(i, j);
+                    let rhs = rhs.get_unchecked(i, j);
+                    *e = f(*e, *rhs)
+                }
+            }
+        }
+    }
+
+
+    /// Replaces each component of `self` by the result of a closure `f` applied on its components
+    /// joined with the components from `b` and `c`.
+    #[inline]
+    pub fn zip_zip_apply<N2, R2, C2, S2, N3, R3, C3, S3>(&mut self, b: Matrix<N2, R2, C2, S2>, c: Matrix<N3, R3, C3, S3>, mut f: impl FnMut(N, N2, N3) -> N)
+        where N2: Scalar,
+              R2: Dim,
+              C2: Dim,
+              S2: Storage<N2, R2, C2>,
+              N3: Scalar,
+              R3: Dim,
+              C3: Dim,
+              S3: Storage<N3, R3, C3>,
+              ShapeConstraint: SameNumberOfRows<R, R2> + SameNumberOfColumns<C, C2>,
+              ShapeConstraint: SameNumberOfRows<R, R2> + SameNumberOfColumns<C, C2> {
+        let (nrows, ncols) = self.shape();
+
+        assert!(
+            (nrows, ncols) == b.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+        assert!(
+            (nrows, ncols) == c.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+
+        for j in 0..ncols {
+            for i in 0..nrows {
+                unsafe {
+                    let e = self.data.get_unchecked_mut(i, j);
+                    let b = b.get_unchecked(i, j);
+                    let c = c.get_unchecked(i, j);
+                    *e = f(*e, *b, *c)
+                }
+            }
+        }
+    }
 }
 
 impl<N: Scalar, D: Dim, S: Storage<N, D>> Vector<N, D, S> {