From 7f152f40b54988c1387caa9372428c785668c7b0 Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Sun, 21 Aug 2022 14:15:18 +0200
Subject: [PATCH] Backport PR #23695: Document polar handling of
 _interpolation_steps.

---
 lib/matplotlib/projections/polar.py | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
index 3c80ae3ca141..f5c42d4e7bed 100644
--- a/lib/matplotlib/projections/polar.py
+++ b/lib/matplotlib/projections/polar.py
@@ -17,11 +17,16 @@
 
 class PolarTransform(mtransforms.Transform):
     """
-    The base polar transform.  This handles projection *theta* and
-    *r* into Cartesian coordinate space *x* and *y*, but does not
-    perform the ultimate affine transformation into the correct
-    position.
+    The base polar transform.
+
+    This transform maps polar coordinates ``(theta, r)`` into Cartesian
+    coordinates ``(x, y) = (r * cos(theta), r * sin(theta))`` (but does not
+    handle positioning in screen space).
+
+    Path segments at a fixed radius are automatically transformed to circular
+    arcs as long as ``path._interpolation_steps > 1``.
     """
+
     input_dims = output_dims = 2
 
     def __init__(self, axis=None, use_rmin=True,