From c3baa36fb71c3a13f5cc7ad76287f9e2295b323d Mon Sep 17 00:00:00 2001
From: Dimitri Tayo Fongang Wembe <dimitri.wembe.tayo@fau.de>
Date: Tue, 16 May 2023 16:07:54 +0200
Subject: [PATCH] fix mistake in formula of Q in QR-split
---
qr.py | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/qr.py b/qr.py
index ebe08b6..cdb0698 100644
--- a/qr.py
+++ b/qr.py
@@ -16,8 +16,12 @@ def givens_rotation(A, i, j):
np.ndarray: Rotation Matrix ``J`` as above.
"""
# TODO
- c = abs(A[j][j]) / ((A[i][j] ** 2 + A[j][j] ** 2) ** 0.5)
- s = abs(A[i][j]) / ((A[i][j] ** 2 + A[j][j] ** 2) ** 0.5)
+ if abs(A[j][j]) == 0.0:
+ p = ((A[i][j] ** 2 + A[j][j] ** 2) ** 0.5)
+ else:
+ p = np.sign(A[j][j]) * ((A[i][j] ** 2 + A[j][j] ** 2) ** 0.5)
+ c = A[j][j] / p
+ s = A[i][j] / p
n, m = np.shape(A)
J = np.eye(n)
J[j][j] = c
@@ -99,7 +103,15 @@ def main():
Hier kann beliebiger Testcode stehen, der bei der Korrektur vollständig
ignoriert wird.
"""
- pass
+ arr1 = np.array(([3, -4], [3, 5]))
+ J1 = givens_rotation(arr1, 1, 0)
+ arr2 = np.array(([3, 4], [3, 5]))
+ J2 = givens_rotation(arr2, 1, 0)
+ Q, R = qr_decompose(arr1)
+ print(f"J1= {J1}")
+ print(f"J2= {J2}")
+ print(f"J1*arr= {np.dot(J1, arr1)}")
+ print(f"J2*arr= {np.dot(J2, arr2)}")
if __name__ == "__main__": main()
\ No newline at end of file
--
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