Add `try_[zip_[zip_]map` methods to Matrix

Useful for functions that can fail
- integer `_checked` methods
- fallible conversions

src/base/matrix.rs

@@ -718,6 +718,35 @@ impl<T, R: Dim, C: Dim, S: RawStorage<T, R, C>> Matrix<T, R, C, S> {
         unsafe { res.assume_init() }
     }
 
+    /// Returns a matrix containing the `Some` result of `f` applied to each of its entries.
+    /// If `f` returns `None` for any entry, this function returns `None`.
+    #[inline]
+    #[must_use]
+    pub fn try_map<T2: Scalar, F: FnMut(T) -> Option<T2>>(
+        &self,
+        mut f: F,
+    ) -> Option<OMatrix<T2, R, C>>
+    where
+        T: Scalar,
+        DefaultAllocator: Allocator<T2, R, C>,
+    {
+        let (nrows, ncols) = self.shape_generic();
+        let mut res = Matrix::uninit(nrows, ncols);
+
+        for j in 0..ncols.value() {
+            for i in 0..nrows.value() {
+                // Safety: all indices are in range.
+                unsafe {
+                    let a = self.data.get_unchecked(i, j).clone();
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a)?);
+                }
+            }
+        }
+
+        // Safety: res is now fully initialized.
+        Some(unsafe { res.assume_init() })
+    }
+
     /// Cast the components of `self` to another type.
     ///
     /// # Example
@@ -824,6 +853,48 @@ impl<T, R: Dim, C: Dim, S: RawStorage<T, R, C>> Matrix<T, R, C, S> {
         unsafe { res.assume_init() }
     }
 
+    /// Returns a matrix containing the `Some` result of `f` applied to entries of `self`
+    /// and `rhs`.
+    /// If `f` returns `None` for any entry, this function returns `None`.
+    #[inline]
+    #[must_use]
+    pub fn try_zip_map<T2, N3, S2, F>(
+        &self,
+        rhs: &Matrix<T2, R, C, S2>,
+        mut f: F,
+    ) -> Option<OMatrix<N3, R, C>>
+    where
+        T: Scalar,
+        T2: Scalar,
+        N3: Scalar,
+        S2: RawStorage<T2, R, C>,
+        F: FnMut(T, T2) -> Option<N3>,
+        DefaultAllocator: Allocator<N3, R, C>,
+    {
+        let (nrows, ncols) = self.shape_generic();
+        let mut res = Matrix::uninit(nrows, ncols);
+
+        assert_eq!(
+            (nrows.value(), ncols.value()),
+            rhs.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+
+        for j in 0..ncols.value() {
+            for i in 0..nrows.value() {
+                // Safety: all indices are in range.
+                unsafe {
+                    let a = self.data.get_unchecked(i, j).clone();
+                    let b = rhs.data.get_unchecked(i, j).clone();
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a, b)?)
+                }
+            }
+        }
+
+        // Safety: res is now fully initialized.
+        Some(unsafe { res.assume_init() })
+    }
+
     /// Returns a matrix containing the result of `f` applied to each entries of `self` and
     /// `b`, and `c`.
     #[inline]
@@ -874,6 +945,57 @@ impl<T, R: Dim, C: Dim, S: RawStorage<T, R, C>> Matrix<T, R, C, S> {
         unsafe { res.assume_init() }
     }
 
+    /// Returns a matrix containing the `Some` result of `f` applied to entries of `self`
+    /// and `b`, and `c`.
+    /// If `f` returns `None` for any entry, this function returns `None`.
+    #[inline]
+    #[must_use]
+    pub fn try_zip_zip_map<T2, N3, N4, S2, S3, F>(
+        &self,
+        b: &Matrix<T2, R, C, S2>,
+        c: &Matrix<N3, R, C, S3>,
+        mut f: F,
+    ) -> Option<OMatrix<N4, R, C>>
+    where
+        T: Scalar,
+        T2: Scalar,
+        N3: Scalar,
+        N4: Scalar,
+        S2: RawStorage<T2, R, C>,
+        S3: RawStorage<N3, R, C>,
+        F: FnMut(T, T2, N3) -> Option<N4>,
+        DefaultAllocator: Allocator<N4, R, C>,
+    {
+        let (nrows, ncols) = self.shape_generic();
+        let mut res = Matrix::uninit(nrows, ncols);
+
+        assert_eq!(
+            (nrows.value(), ncols.value()),
+            b.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+        assert_eq!(
+            (nrows.value(), ncols.value()),
+            c.shape(),
+            "Matrix simultaneous traversal error: dimension mismatch."
+        );
+
+        for j in 0..ncols.value() {
+            for i in 0..nrows.value() {
+                // Safety: all indices are in range.
+                unsafe {
+                    let a = self.data.get_unchecked(i, j).clone();
+                    let b = b.data.get_unchecked(i, j).clone();
+                    let c = c.data.get_unchecked(i, j).clone();
+                    *res.data.get_unchecked_mut(i, j) = MaybeUninit::new(f(a, b, c)?)
+                }
+            }
+        }
+
+        // Safety: res is now fully initialized.
+        Some(unsafe { res.assume_init() })
+    }
+
     /// Folds a function `f` on each entry of `self`.
     #[inline]
     #[must_use]