Merge pull request matplotlib#26216 from QuLogic/auto-backport-of-pr-26126-on-v3.7.x

Backport PR matplotlib#26126 on branch v3.7.x (Revert "Merge pull request matplotlib#24555 from parthpankajtiwary/symlog-warn")

Author: QuLogic

lib/matplotlib/scale.py

@@ -389,11 +389,6 @@ def __init__(self, base, linthresh, linscale):
 
     def transform_non_affine(self, a):
         abs_a = np.abs(a)
-        if (abs_a < self.linthresh).all():
-            _api.warn_external(
-                "All values for SymLogScale are below linthresh, making "
-                "it effectively linear. You likely should lower the value "
-                "of linthresh. ")
         with np.errstate(divide="ignore", invalid="ignore"):
             out = np.sign(a) * self.linthresh * (
                 np.power(self.base,

lib/matplotlib/tests/test_scale.py

@@ -55,20 +55,6 @@ def test_symlog_mask_nan():
     assert type(out) == type(x)
 
 
-def test_symlog_linthresh():
-    np.random.seed(19680801)
-    x = np.random.random(100)
-    y = np.random.random(100)
-
-    fig, ax = plt.subplots()
-    plt.plot(x, y, 'o')
-    ax.set_xscale('symlog')
-    ax.set_yscale('symlog')
-
-    with pytest.warns(UserWarning, match="All values .* of linthresh"):
-        fig.canvas.draw()
-
-
 @image_comparison(['logit_scales.png'], remove_text=True)
 def test_logit_scales():
     fig, ax = plt.subplots()