numpy bitwise operation error

Question

numpy version 1.9.0

1 & (2**63)
0

np.bitwise_and(1, 2**63)
TypeError: ufunc 'bitwise_and' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

np.bitwise_and(1, 2**63 + 100)
TypeError: ufunc 'bitwise_and' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

np.bitwise_and(1, 2**64)
0

Is this a bug or am I missing something?

HYRY · Accepted Answer · 2014-11-05 13:46:45Z

7

convert to uint64 first:

np.bitwise_and(np.uint64(1), np.uint64(2**63))

Here is the code to check the rule to convert python integer to numpy integer:

print np.array([2**30]).dtype
print np.array([2**31]).dtype
print np.array([2**63]).dtype
print np.array([2**64]).dtype

output:

int32
int64
uint64
object

I think np.bitwise_and(1, 2**63) raise error because 2**63 is out of the range of int32 and int64.

np.bitwise_and(1, 2**64) works because it will use Python's long object.

We need to read the source code to understand the detail.

edited Nov 5, 2014 at 13:46

answered Nov 5, 2014 at 10:52

HYRY

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1 Comment

jf328 Over a year ago

It works. Do you think this is a bug or is there a reason that a manual convert is needed here? Note that 2**64 doesn't have any problem.

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