From 2f7edc08fc8ac7e3c815c1385f2c25a22b683c74 Mon Sep 17 00:00:00 2001
From: Forrest Hilton <forrestmhilton@gmail.com>
Date: Wed, 5 Jul 2023 00:18:53 -0500
Subject: [PATCH 1/2] fix: mandelbrot_plot crashes when given polynomials with
 parametric critical points

---
 .../complex_dynamics/mandel_julia_helper.pyx         | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx b/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
index 987308e5cb1..2b05648239a 100644
--- a/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
+++ b/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
@@ -680,6 +680,15 @@ cpdef polynomial_mandelbrot(f, parameter=None, double x_center=0,
         sage: f = z^4 - z + c
         sage: polynomial_mandelbrot(f, pixel_count=100)
         100x100px 24-bit RGB image
+
+    ::
+
+        sage: from sage.dynamics.complex_dynamics.mandel_julia_helper import polynomial_mandelbrot
+        sage: B.<c> = CC[]
+        sage: R.<z> = B[]
+        sage: f = z^2*(z-c) + c
+        sage: polynomial_mandelbrot(f, pixel_count=100)
+        100x100px 24-bit RGB image
     """
 
     cdef:
@@ -763,8 +772,9 @@ cpdef polynomial_mandelbrot(f, parameter=None, double x_center=0,
         df = f.derivative(z).univariate_polynomial()
         critical_pts = df.roots(multiplicities=False)
         constant_c = True
-    except PariError:
+    except (PariError, TypeError):
         constant_c = False
+        critical_pts = []
 
     # If c is in the constant term of the polynomial, then the critical points
     # will be independent of c.

From 7906e8860164da2a7da73ba6f0a6564c451b890c Mon Sep 17 00:00:00 2001
From: Forrest Hilton <forrestmhilton@gmail.com>
Date: Thu, 27 Jul 2023 14:27:08 -0500
Subject: [PATCH 2/2] redundant line

---
 src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx b/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
index 2b05648239a..62788943b09 100644
--- a/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
+++ b/src/sage/dynamics/complex_dynamics/mandel_julia_helper.pyx
@@ -774,7 +774,6 @@ cpdef polynomial_mandelbrot(f, parameter=None, double x_center=0,
         constant_c = True
     except (PariError, TypeError):
         constant_c = False
-        critical_pts = []
 
     # If c is in the constant term of the polynomial, then the critical points
     # will be independent of c.