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 | 1 | initial version |
The bitwise not in python is supposed to be ~ (see https://wiki.python.org/moin/BitwiseOperators about how negative numbers are encoded), but Sage's preparser first transforms 0b1000 as an element of ZZ for which the action of ~ is the multiplicative inverse:
sage: ~0b1000
1/8
This is because, in Sage:
sage: 0b1000.parent()
Integer Ring
sage: preparse("0b1000")
"Integer('1000', 2)"
You can get the python behaviour you can either turn the sage preparser off:
sage: preparser(False)
sage: ~0b1000
-9
or explicitely use python int:
sage: ~int(0b1000)
-9
Another workaround is to notice that not a is the same as a xor 1.
| | 2 | No.2 Revision |
The bitwise not not in python Python is supposed to be ~ (see https://wiki.python.org/moin/BitwiseOperators about how negative numbers are encoded), but Sage's preparser first transforms 0b1000 as an element of ZZ for which the action of ~ is the multiplicative inverse:
sage: ~0b1000
1/8
This is because, in Sage:
sage: 0b1000.parent()
Integer Ring
sage: preparse("0b1000")
"Integer('1000', 2)"
You can To get the python behaviour behaviour, you can either turn the sage preparser off:
sage: preparser(False)
sage: ~0b1000
-9
or explicitely use python int:
sage: ~int(0b1000)
-9
Another workaround is to notice that not a is the same as a xor 1.
