'iformat', 'dformat', 'zformat'
that control, respectively, how integer, double and complex numbers are
printed. The fields are C printf format strings with default
values '5.4e' for 'd' and 'z' matrices and '5i' for
'i' matrices.
>>> from cvxopt.base import matrix, print_options
>>> print_options
{'zformat': '5.4e', 'iformat': '5i', 'dformat': '5.4e'}
>>> A = matrix([1., 2., 3.])
>>> print A
1.0000e+00
2.0000e+00
3.0000e+00
>>> print_options['dformat'] = 'f'
>>> print A
1.000000
2.000000
3.000000
>>> print_options['dformat'] = '5.2e'
>>> print A
1.00e+00
2.00e+00
3.00e+00