QR decomposition: Difference between revisions
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(Python solution) |
m (→{{header|Python}}: Add note on Numpy qr function.) |
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=={{header|Python}}== |
=={{header|Python}}== |
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{{libheader|numpy}} |
{{libheader|numpy}} |
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Numpy has a qr function but here is a reimplementation to show construction and use of the Householder reflections. |
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<lang python>#!/usr/bin/env python3 |
<lang python>#!/usr/bin/env python3 |
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( 6, 167, -68), |
( 6, 167, -68), |
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(-4, 24, -41), |
(-4, 24, -41), |
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))) |
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)), dtype=np.float64) |
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q, r = qr(a) |
q, r = qr(a) |
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return np.linalg.solve(r[:n, :], np.dot(q.T, b)[:n]) |
return np.linalg.solve(r[:n, :], np.dot(q.T, b)[:n]) |
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x = np.array((0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) |
x = np.array((0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)) |
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y = np.array((1, 6, 17, 34, 57, 86, 121, 162, 209, 262, 321) |
y = np.array((1, 6, 17, 34, 57, 86, 121, 162, 209, 262, 321)) |
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print('\npolyfit:\n', polyfit(x, y, 2))</lang> |
print('\npolyfit:\n', polyfit(x, y, 2))</lang> |
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