python complex number print result different from shell output

Question

>>> a=4.
>>> b=3.
r = sqrt(a ** 2 + b ** 2)
x = atan(b/a)
a = r * cos(x)
b = r * sin(x)
k = 0
y = (2 * pi * k + x) /3

root1 = r ** (1./3) * ( cos(y)+ 1j * sin(y) )
root11 = root1**4/root1
>>> root11
(3.999999999999999+2.999999999999999j)
>>> print root11
(4+3j)

How do I print out this complex number in this '(3.999999999999999+2.999999999999999j)' form? I tried

>>> print '%15f %15fi' % (root11.real, root11.imag)
4.000000        3.000000i

please help

possible duplicate of [Strange behaviour with floats and string conversion](http://stackoverflow.com/questions/13345334/strange-behaviour-with-floats-and-string-conversion) — Ashwini Chaudhary, Jun 03 '13 at 02:58
because `print` (actually `float.__str__`) and `%15f` are rounding the number — JBernardo, Jun 03 '13 at 02:59
Python 3 seems to print `(3.999999999999999+2.999999999999999j)`. — Mechanical snail, Jun 03 '13 at 02:59

score 2 · Answer 1 · answered Jun 03 '13 at 05:28

2

You may also use the new format syntax,

print "{0:.15f}+{1:.15f}i".format(root11.real, root11.imag)

answered Jun 03 '13 at 05:28

phil1710

51
4

score 1 · Answer 2 · edited Jun 03 '13 at 04:00

1

You should use

print '%.15f %.15fi' % (root11.real, root11.imag)

Notice there is a . before the 15f to format the precision after the decimal. If you do not have the ., you are specifying the field width.

In my machine (Python 2.7.3), The result is:

3.999999999999999 2.999999999999999i

edited Jun 03 '13 at 04:00

dawg

98,345
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answered Jun 03 '13 at 03:29

Tanky Woo

4,906
9
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score 1 · Accepted Answer · answered Jun 03 '13 at 08:34

1

As one of the comments suggest print root11.__repr__() works perfectly

answered Jun 03 '13 at 08:34

pythoniku

3,532
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python complex number print result different from shell output

3 Answers3