matplotlib
diff --git a/‎lib/matplotlib/axes/_axes.py
Lines changed: 6 additions & 2 deletions b/‎lib/matplotlib/axes/_axes.py
Lines changed: 6 additions & 2 deletions
diff --git a/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.pdf
1.56 KB b/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.pdf
1.56 KB
diff --git a/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.png
14.7 KB b/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.png
14.7 KB
diff --git a/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.svg
Lines changed: 212 additions & 0 deletions b/‎lib/matplotlib/tests/baseline_images/test_axes/fill_between_interpolate_decreasing.svg
Lines changed: 212 additions & 0 deletions
diff --git a/‎lib/matplotlib/tests/test_axes.py
Lines changed: 22 additions & 0 deletions b/‎lib/matplotlib/tests/test_axes.py
Lines changed: 22 additions & 0 deletions
@@ -4876,7 +4876,9 @@ def get_interp_point(ind):
                     diff_order = diff_values.argsort()
                     diff_root_x = np.interp(
                         0, diff_values[diff_order], x_values[diff_order])
-                    diff_root_y = np.interp(diff_root_x, x_values, y1_values)
+                    x_order = x_values.argsort()
+                    diff_root_y = np.interp(diff_root_x, x_values[x_order],
+                                            y1_values[x_order])
                     return diff_root_x, diff_root_y
 
                 start = get_interp_point(ind0)
@@ -5026,7 +5028,9 @@ def get_interp_point(ind):
                     diff_order = diff_values.argsort()
                     diff_root_y = np.interp(
                         0, diff_values[diff_order], y_values[diff_order])
-                    diff_root_x = np.interp(diff_root_y, y_values, x1_values)
+                    y_order = y_values.argsort()
+                    diff_root_x = np.interp(diff_root_y, y_values[y_order],
+                                            x1_values[y_order])
                     return diff_root_x, diff_root_y
 
                 start = get_interp_point(ind0)
 
@@ -968,6 +968,28 @@ def test_fill_between_interpolate():
                      interpolate=True)
 
 
+@image_comparison(baseline_images=['fill_between_interpolate_decreasing'],
+                  style='mpl20', remove_text=True)
+def test_fill_between_interpolate_decreasing():
+    p = np.array([724.3, 700, 655])
+    t = np.array([9.4, 7, 2.2])
+    prof = np.array([7.9, 6.6, 3.8])
+
+    fig = plt.figure(figsize=(9, 9))
+    ax = fig.add_subplot(1, 1, 1)
+
+    ax.plot(t, p, 'tab:red')
+    ax.plot(prof, p, 'k')
+
+    ax.fill_betweenx(p, t, prof, where=prof < t,
+                     facecolor='blue', interpolate=True, alpha=0.4)
+    ax.fill_betweenx(p, t, prof, where=prof > t,
+                     facecolor='red', interpolate=True, alpha=0.4)
+
+    ax.set_xlim(0, 30)
+    ax.set_ylim(800, 600)
+
+
 @image_comparison(baseline_images=['symlog'])
 def test_symlog():
     x = np.array([0, 1, 2, 4, 6, 9, 12, 24])