File:Newton-Raphson method.gif
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![File:Newton-Raphson method.gif](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Newton-Raphson_method.gif/800px-Newton-Raphson_method.gif?20220129153027)
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Summary
[edit]DescriptionNewton-Raphson method.gif |
English: Newton-Raphson method to find a zero of f(x) = x2 - 2 |
Date | |
Source | Own work |
Author | ARAKI Satoru |
import numpy as np
import matplotlib.pyplot as plt
import imageio
plt.rcParams['text.usetex'] = True
plt.rcParams['xtick.direction'] = 'in'
plt.rcParams['ytick.direction'] = 'in'
a = 1.0
b = 3.0
f = lambda x: x**2 - 2.0
xs = np.arange(a, b, step=0.01)
ys = f(xs)
# Newton-Raphson method
N = 6
F = lambda x: x - (x**2 - 2.0)/(2.0*x)
x = [ 2.0 ]
for n in range(1, N + 1):
x.append(F(x[n - 1]))
y = [ f(xn) for xn in x ]
T = 4*N
alpha = 0.3
blue = 'tab:blue'
orange = 'tab:orange'
for t in range(T - 3):
n = t//4
# graph y = x^2 - 2
plt.plot(xs, ys, color=blue)
plt.xlim(1.35, 2.05)
plt.ylim(-0.2, 2.2)
plt.xlabel(r'$x$')
plt.ylabel(r'$y$')
plt.title(r'Newton-Raphson method to find a zero of $f(x) = x^2 - 2$')
# line y = 0
plt.plot(xs, 0*ys, color=blue)
# main animation
for m in range(n + 1):
# points x^(n)
plt.plot(x[m], 0.0, 'o', color=orange, alpha=alpha)
for m in range(n):
# vertical line segments + points f(x^(n)) + tangent line segments
plt.plot([ x[m], x[m] ], [ 0, y[m] ], color=orange, alpha=alpha)
plt.plot(x[m], y[m], 'o', color=orange, alpha=alpha)
plt.plot([ x[m + 1], x[m] ], [ 0, y[m] ], color=orange, alpha=alpha)
if t % 4 == 0:
# point x^(n) + text label
plt.plot(x[n], 0.0, 'o', color=orange)
plt.text(x[n] - 0.01, -0.15, r'$x^{(' + f'{n}' + r')}$')
elif t % 4 == 1:
# vertical line segment
plt.plot([ x[n], x[n] ], [ 0, y[n] ], color=orange)
elif t % 4 == 2:
# point f(x^(n)) + text label (+ vertical line segment)
plt.plot(x[n], y[n], 'o', color=orange)
plt.text(x[n] - 0.04, y[n] + 0.1, r'$f(x^{(' + f'{n}' + r')})$')
plt.plot([ x[n], x[n] ], [ 0, y[n] ], color=orange, alpha=alpha)
elif t % 4 == 3:
# tangent line segment (+ point f(x^(n)) + vertical line segment)
plt.plot([ x[n + 1], x[n] ], [ 0, y[n] ], color=orange)
plt.plot(x[n], y[n], 'o', color=orange, alpha=alpha)
plt.plot([ x[n], x[n] ], [ 0, y[n] ], color=orange, alpha=alpha)
# numerical results
plt.text(1.407, 1.8, r'$\sqrt{2} = 1.414213562373095$')
for m in range(n + 1):
plt.text(1.400, 1.7 - 0.1*m, r'$x^{(' + f'{m}' + r')} = ' + f'{round(x[m], 15)}'.ljust(2 + 15, '0') + r'$')
plt.savefig(f'{t}.png', dpi=300)
plt.close()
filenames = [ f'{t}.png' for t in range(T - 3) ]
with imageio.get_writer('newton_raphson_method.gif', mode='I', fps=1) as writer:
for filename in filenames:
image = imageio.imread(filename)
writer.append_data(image)
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[edit]I, the copyright holder of this work, hereby publish it under the following license:
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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.
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Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 15:30, 29 January 2022 | ![]() | 1,920 × 1,440 (1.1 MB) | ARAKI Satoru (talk | contribs) | Uploaded own work with UploadWizard |
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