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[Octave-bug-tracker] [bug #66652] Element power operator introduces nume
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From: |
Dmitri A. Sergatskov |
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Subject: |
[Octave-bug-tracker] [bug #66652] Element power operator introduces numerical error when broadcasting |
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Date: |
Fri, 10 Jan 2025 14:18:35 -0500 (EST) |
Follow-up Comment #2, bug #66652 (group octave):
On MacOS octave 10 there is no difference:
octave:1> # exponent vector
p = [2 1 0]
# scalar .^ vector is correct
x = i .^ p, x - round(x)
x = (2i) .^ p, x - round(x)
x = (3i) .^ p, x - round(x)
# column vector .^ row vector has numerical error
x = [i; 2i; 3i] .^ p, x - round(x)
# expanding vectors to full matrix is correct again
x = [i i i; 2i 2i 2i; 3i 3i 3i] .^ [2 1 0; 2 1 0; 2 1 0]
x - round (x)
p =
2 1 0
x =
-1.0000 + 0.0000i 0.0000 + 1.0000i 1.0000 + 0i
ans =
0 + 1.2246e-16i 6.1232e-17 + 0i 0 +
0i
x =
-4.0000 + 0.0000i 0.0000 + 2.0000i 1.0000 + 0i
ans =
0 + 4.8986e-16i 1.2246e-16 + 0i 0 +
0i
x =
-9.0000 + 0.0000i 0.0000 + 3.0000i 1.0000 + 0i
ans =
-1.7764e-15 + 1.1022e-15i 1.8370e-16 + 4.4409e-16i 0 +
0i
x =
-1.0000 + 0.0000i 0.0000 + 1.0000i 1.0000 + 0i
-4.0000 + 0.0000i 0.0000 + 2.0000i 1.0000 + 0i
-9.0000 + 0.0000i 0.0000 + 3.0000i 1.0000 + 0i
ans =
0 + 1.2246e-16i 6.1232e-17 + 0i 0 +
0i
0 + 4.8986e-16i 1.2246e-16 + 0i 0 +
0i
-1.7764e-15 + 1.1022e-15i 1.8370e-16 + 4.4409e-16i 0 +
0i
x =
-1.0000 + 0.0000i 0.0000 + 1.0000i 1.0000 + 0i
-4.0000 + 0.0000i 0.0000 + 2.0000i 1.0000 + 0i
-9.0000 + 0.0000i 0.0000 + 3.0000i 1.0000 + 0i
ans =
0 + 1.2246e-16i 6.1232e-17 + 0i 0 +
0i
0 + 4.8986e-16i 1.2246e-16 + 0i 0 +
0i
-1.7764e-15 + 1.1022e-15i 1.8370e-16 + 4.4409e-16i 0 +
0i
octave:8> x = [i i i; 2i 2i 2i; 3i 3i 3i] .^ [2 1 0; 2 1 0; 2 1 0], x - round
(x)
x =
-1.0000 + 0.0000i 0.0000 + 1.0000i 1.0000 + 0i
-4.0000 + 0.0000i 0.0000 + 2.0000i 1.0000 + 0i
-9.0000 + 0.0000i 0.0000 + 3.0000i 1.0000 + 0i
ans =
0 + 1.2246e-16i 6.1232e-17 + 0i 0 +
0i
0 + 4.8986e-16i 1.2246e-16 + 0i 0 +
0i
-1.7764e-15 + 1.1022e-15i 1.8370e-16 + 4.4409e-16i 0 +
0i
octave:9> x = [i; 2i; 3i] .^ [2 1 0], x - round (x)
x =
-1.0000 + 0.0000i 0.0000 + 1.0000i 1.0000 + 0i
-4.0000 + 0.0000i 0.0000 + 2.0000i 1.0000 + 0i
-9.0000 + 0.0000i 0.0000 + 3.0000i 1.0000 + 0i
ans =
0 + 1.2246e-16i 6.1232e-17 + 0i 0 +
0i
0 + 4.8986e-16i 1.2246e-16 + 0i 0 +
0i
-1.7764e-15 + 1.1022e-15i 1.8370e-16 + 4.4409e-16i 0 +
0i
octave:10>
Dmitri.
--
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