Changed loops order in from_fn_generic

benches/core/matrix.rs

@@ -186,3 +186,21 @@ fn mat_mul_mat(bench: &mut Bencher) {
         test::black_box(a.mul_to(&b, &mut ab));
     })
 }
+
+#[bench]
+fn mat100_from_fn(bench: &mut Bencher) {
+    bench.iter(|| {
+        DMatrix::from_fn(100, 100, |a, b| {
+            a + b
+        });
+    })
+}
+
+#[bench]
+fn mat500_from_fn(bench: &mut Bencher) {
+    bench.iter(|| {
+        DMatrix::from_fn(500, 500, |a, b| {
+            a + b
+        });
+    })
+}

src/base/construction.rs

@@ -108,8 +108,8 @@ where
     {
         let mut res = unsafe { Self::new_uninitialized_generic(nrows, ncols) };
 
-        for i in 0..nrows.value() {
+        for j in 0..ncols.value() {
-            for j in 0..ncols.value() {
+            for i in 0..nrows.value() {
                 unsafe { *res.get_unchecked_mut(i, j) = f(i, j) }
             }
         }