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Why is (inf + 0j)*1 == inf + nanj?
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>>> from numpy import inf, nan
>>> z = (inf+0j)*1
(inf+nanj)
Why? This caused a nasty bug in my code.
python numpy nan ieee-754
add a comment
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>>> from numpy import inf, nan
>>> z = (inf+0j)*1
(inf+nanj)
Why? This caused a nasty bug in my code.
python numpy nan ieee-754
add a comment
|
>>> from numpy import inf, nan
>>> z = (inf+0j)*1
(inf+nanj)
Why? This caused a nasty bug in my code.
python numpy nan ieee-754
>>> from numpy import inf, nan
>>> z = (inf+0j)*1
(inf+nanj)
Why? This caused a nasty bug in my code.
python numpy nan ieee-754
python numpy nan ieee-754
asked 8 hours ago
marnixmarnix
926 bronze badges
926 bronze badges
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2 Answers
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The 1 is converted to a complex number first, 1 + 0j, which then leads to an inf * 0 multiplication, resulting in a nan.
(inf + 0j) * 1
(inf + 0j) * (1 + 0j)
inf * 1 + inf * 0j + 0j * 1 + 0j * 0j
# ^ this is where it comes from
inf + nan j + 0j + 0
inf + nan j
3
For answering the question "why...?", probably the important most step is the first one, where1is cast to1 + 0j.
– Warren Weckesser
8 hours ago
add a comment
|
"Why is (inf + 0j)*1 == inf + nanj"
Actually, it isn't:
from math import inf
(inf+0j)*1==complex("inf+nanj")
# False
On a more serious note, to find the "true" reason---as opposed to the purely mechanical reason given in the accepted answer---one probably has to start with something like https://math.stackexchange.com/q/628947
Yeah, becausenan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.
– cmaster
27 mins ago
add a comment
|
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
The 1 is converted to a complex number first, 1 + 0j, which then leads to an inf * 0 multiplication, resulting in a nan.
(inf + 0j) * 1
(inf + 0j) * (1 + 0j)
inf * 1 + inf * 0j + 0j * 1 + 0j * 0j
# ^ this is where it comes from
inf + nan j + 0j + 0
inf + nan j
3
For answering the question "why...?", probably the important most step is the first one, where1is cast to1 + 0j.
– Warren Weckesser
8 hours ago
add a comment
|
The 1 is converted to a complex number first, 1 + 0j, which then leads to an inf * 0 multiplication, resulting in a nan.
(inf + 0j) * 1
(inf + 0j) * (1 + 0j)
inf * 1 + inf * 0j + 0j * 1 + 0j * 0j
# ^ this is where it comes from
inf + nan j + 0j + 0
inf + nan j
3
For answering the question "why...?", probably the important most step is the first one, where1is cast to1 + 0j.
– Warren Weckesser
8 hours ago
add a comment
|
The 1 is converted to a complex number first, 1 + 0j, which then leads to an inf * 0 multiplication, resulting in a nan.
(inf + 0j) * 1
(inf + 0j) * (1 + 0j)
inf * 1 + inf * 0j + 0j * 1 + 0j * 0j
# ^ this is where it comes from
inf + nan j + 0j + 0
inf + nan j
The 1 is converted to a complex number first, 1 + 0j, which then leads to an inf * 0 multiplication, resulting in a nan.
(inf + 0j) * 1
(inf + 0j) * (1 + 0j)
inf * 1 + inf * 0j + 0j * 1 + 0j * 0j
# ^ this is where it comes from
inf + nan j + 0j + 0
inf + nan j
edited 8 hours ago
Engineero
7,3543 gold badges26 silver badges52 bronze badges
7,3543 gold badges26 silver badges52 bronze badges
answered 8 hours ago
MaratMarat
4,9371 gold badge20 silver badges34 bronze badges
4,9371 gold badge20 silver badges34 bronze badges
3
For answering the question "why...?", probably the important most step is the first one, where1is cast to1 + 0j.
– Warren Weckesser
8 hours ago
add a comment
|
3
For answering the question "why...?", probably the important most step is the first one, where1is cast to1 + 0j.
– Warren Weckesser
8 hours ago
3
3
For answering the question "why...?", probably the important most step is the first one, where
1 is cast to 1 + 0j.– Warren Weckesser
8 hours ago
For answering the question "why...?", probably the important most step is the first one, where
1 is cast to 1 + 0j.– Warren Weckesser
8 hours ago
add a comment
|
"Why is (inf + 0j)*1 == inf + nanj"
Actually, it isn't:
from math import inf
(inf+0j)*1==complex("inf+nanj")
# False
On a more serious note, to find the "true" reason---as opposed to the purely mechanical reason given in the accepted answer---one probably has to start with something like https://math.stackexchange.com/q/628947
Yeah, becausenan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.
– cmaster
27 mins ago
add a comment
|
"Why is (inf + 0j)*1 == inf + nanj"
Actually, it isn't:
from math import inf
(inf+0j)*1==complex("inf+nanj")
# False
On a more serious note, to find the "true" reason---as opposed to the purely mechanical reason given in the accepted answer---one probably has to start with something like https://math.stackexchange.com/q/628947
Yeah, becausenan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.
– cmaster
27 mins ago
add a comment
|
"Why is (inf + 0j)*1 == inf + nanj"
Actually, it isn't:
from math import inf
(inf+0j)*1==complex("inf+nanj")
# False
On a more serious note, to find the "true" reason---as opposed to the purely mechanical reason given in the accepted answer---one probably has to start with something like https://math.stackexchange.com/q/628947
"Why is (inf + 0j)*1 == inf + nanj"
Actually, it isn't:
from math import inf
(inf+0j)*1==complex("inf+nanj")
# False
On a more serious note, to find the "true" reason---as opposed to the purely mechanical reason given in the accepted answer---one probably has to start with something like https://math.stackexchange.com/q/628947
edited 3 hours ago
answered 7 hours ago
Paul PanzerPaul Panzer
35.6k2 gold badges23 silver badges54 bronze badges
35.6k2 gold badges23 silver badges54 bronze badges
Yeah, becausenan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.
– cmaster
27 mins ago
add a comment
|
Yeah, becausenan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.
– cmaster
27 mins ago
Yeah, because
nan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.– cmaster
27 mins ago
Yeah, because
nan != nan. I understand that this answer is half-joking, but I fail to see why it should be helpful to the OP the way it's written.– cmaster
27 mins ago
add a comment
|
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