Hello,
I define a complex-valued function, and then want to plot its absolute
value and argument:
w = var('w')
V(omega) = 1/(I*omega) + 1/2 + (I*omega)
plot(abs(V(w)),(w,0.1,5), axes_labels=['$Frequency$', '$Voltage$']) #
This works, I get the correct plot.
However, I want to plot the argument of this function, and I try:
plot(arg(V(w)),(w,0,5), axes_labels=['$Frequency$', '$Phase$'])
But it gives those errors:
------
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_29.py", line 10, in <module>
exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8
-*-\\n" +
_support_.preparse_worksheet_cell(base64.b64decode("cGxvdChhcmcoVih3KSksKHcsMCw1KSwgYXhlc19sYWJlbHM9WyckRnJlcXVlbmN5JCcsICckUGhhc2UkJ10p"),globals())+"\\n");
execfile(os.path.abspath("___code___.py"))
File "", line 1, in <module>
File "/tmp/tmphudQ36/___code___.py", line 3, in <module>
exec compile(u"plot(arg(V(w)),(w,_sage_const_0 ,_sage_const_5 ),
axes_labels=['$Frequency$', '$Phase$'])" + '\n', '', 'single')
File "", line 1, in <module>
File
"/tools/sage/local/lib/python2.6/site-packages/sage/misc/functional.py",
line 81, in arg
except AttributeError: return CDF(x).arg()
File "complex_double.pyx", line 310, in
sage.rings.complex_double.ComplexDoubleField_class.__call__
(sage/rings/complex_double.c:4190)
File "parent.pyx", line 915, in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:6668)
File "coerce_maps.pyx", line 82, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3119)
File "coerce_maps.pyx", line 77, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3022)
File "complex_double.pyx", line 344, in
sage.rings.complex_double.ComplexDoubleField_class._element_constructor_
(sage/rings/complex_double.c:4592)
File "expression.pyx", line 928, in
sage.symbolic.expression.Expression._complex_double_
(sage/symbolic/expression.cpp:5306)
File "expression.pyx", line 771, in
sage.symbolic.expression.Expression._eval_self
(sage/symbolic/expression.cpp:4763)
TypeError: Cannot evaluate symbolic expression to a numeric value.
------
How do I solve this problem?
I'm using sage 4.6.2.
Thanks!
--
Renan Birck Pinheiro - Grupo de Microeletrônica - Eng. Elétrica/UFSM
http://renanbirck.blogspot.com | http://twitter.com/renan2112
skype: renan.ee.ufsm | msn: [email protected]
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