File:Height function plotted against singular variety of binomial generating function with example contours of integration plotted.png

Summary

Description
English: Graph of height function for different values in the singular variety of . The red dot corresponds to the critical point . The red circles are possible contours of integration for . Reproduction of a graph from Pemantle, Robin; Wilson, Mark C.; Melczer, Stephen (2024). Analytic Combinatorics in Several Variables (PDF) (2nd ed.). Cambridge University Press. pp. 196.
Date
Source Own work
Author Dom walden
PNG development
InfoField
Source code
InfoField

Python code

import matplotlib.pyplot as plt
import numpy as np

def height(x, y, r = [1, 1]):
    return - r[0] * np.log(abs(x)) - r[1] * np.log(abs(y))

fig, ax = plt.subplots(subplot_kw={'projection': '3d', 'computed_zorder': False})

x = np.arange(-0.5, 1.5, 0.01)
y = np.arange(-1, 1, 0.01)
X, Y = np.meshgrid(x, y)
z = X + 1j*Y
ax.plot_surface(X, Y, height(z, 1 - z), zorder=0)

ax.scatter(0.5, 0, height(1/2, 1/2), color='red')

theta = np.arange(0, 2 * np.pi, 0.01)
r = 1/10
z = r*np.e**(1j*theta)
x = np.real(z)
y = np.imag(z)
ax.plot(x, y, height(z, 1 - z), c='red')

r = 1/5
z = r*np.e**(1j*theta)
x = np.real(z)
y = np.imag(z)
ax.plot(x, y, height(z, 1 - z), c='red')

r = 1/2
z = r*np.e**(1j*theta)
x = np.real(z)
y = np.imag(z)
ax.plot(x, y, height(z, 1 - z), c='red')

ax.set_zlim([0, 3])
fig.set_figwidth(10)
fig.set_figheight(10)
plt.tight_layout()

plt.savefig("height_of_binomial_different_v.png")

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
Category:CC-BY-SA-4.0#Height%20function%20plotted%20against%20singular%20variety%20of%20binomial%20generating%20function%20with%20example%20contours%20of%20integration%20plotted.pngCategory:Self-published work
Category:Binomial coefficients Category:Complex analysis
Category:Binomial coefficients Category:CC-BY-SA-4.0 Category:Complex analysis Category:Creative Commons Attribution-Share Alike 4.0 missing SDC copyright license Category:Creative Commons Attribution-Share Alike missing SDC copyright status Category:PNG created with Matplotlib code Category:Pages that use a deprecated format of the math tags Category:Self-published work Category:Self-published work missing SDC copyright license