MAINT: Add test case of strides input & more comments

2 files changed, 13 insertions, 2 deletions

diff --git a/numpy/core/src/umath/simd.inc.src b/numpy/core/src/umath/simd.inc.src
index 501100465..106c7e7c9 100644
--- a/numpy/core/src/umath/simd.inc.src
+++ b/numpy/core/src/umath/simd.inc.src
@@ -2699,9 +2699,10 @@ static NPY_GCC_OPT_3 NPY_GCC_TARGET_@ISA@ void
  * 1) if x > mTH_max or x is INF; return INF (overflow)
  * 2) if x < mTH_min; return 0.0f (underflow)
  * 3) if abs(x) < mTH_nearzero; return 1.0f + x
- * 4) Range reduction:
+ * 4) if x is Nan; return Nan
+ * 5) Range reduction:
  *    x = (32m + j)ln2 / 32 + r; r in [-ln2/64, ln2/64]
- * 5) exp(r) - 1 is approximated by a polynomial function p(r)
+ * 6) exp(r) - 1 is approximated by a polynomial function p(r)
  *    exp(x) = 2^m(2^(j/32) + 2^(j/32)p(r));
  */
 #if defined HAVE_ATTRIBUTE_TARGET_AVX512F_WITH_INTRINSICS
diff --git a/numpy/core/tests/test_umath.py b/numpy/core/tests/test_umath.py
index f8a57d2c2..60c9fe437 100644
--- a/numpy/core/tests/test_umath.py
+++ b/numpy/core/tests/test_umath.py
@@ -640,6 +640,16 @@ class TestExp:
             yf = np.array(y, dtype=dt)*log2_
             assert_almost_equal(np.exp(yf), xf)
 
+    def test_exp_strides(self):
+        np.random.seed(42)
+        strides = np.array([-4,-3,-2,-1,1,2,3,4])
+        sizes = np.arange(2,100)
+        for ii in sizes:
+            x_f64 = np.float64(np.random.uniform(low=0.01, high=709.1,size=ii))
+            y_true = np.exp(x_f64)
+            for jj in strides:
+                assert_array_almost_equal_nulp(np.exp(x_f64[::jj]), y_true[::jj], nulp=2)
+
 class TestSpecialFloats:
     def test_exp_values(self):
         x = [np.nan,  np.nan, np.inf, 0.]