THis got solved really nicely in https://ask.sagemath.org/question/46123/arrow-length-goes-wild-near-poles-in-vector-field-plot/
I posted here because i can not easily post long tracebacks on the forum, and i believed it was important for solving the problem. but it turns out it was me getting mixed up, not a bug (as i suspected). On Saturday, April 13, 2019 at 7:20:24 PM UTC+2, Andreas Schuldei wrote: > > After getting this great tip > > > https://ask.sagemath.org/question/46123/arrow-length-goes-wild-near-poles-in-vector-field-plot/ > > I wanted to use the second approach and changed my code to this: > > ====== > load( 'e-feld.sage') > > pic=phi_ges.subs({ > Q : 1e-9, > d_e : 1, > z_s : .25, > z_c : .5, > epsilon_m : 76, > epsilon_s : 21.75, > epsilon_0 : 8.854187817e-12 > }) > > grad_phi_ges = -phi_ges.gradient([x,z]).simplify() > > pic=grad_phi_ges.subs({ > Q : 1e-9, > d_e : 1, > z_s : .25, > z_c : .5, > epsilon_m : 76, > epsilon_s : 21.75, > epsilon_0 : 8.854187817e-12 > }) > > grad_len = abs(grad_phi_ges) > my_grad = [lambda x,z: grad_phi_ges[0].subs(x=x,z=z) if > grad_len.subs(x=x,z=z) < 7 else None, > lambda x,z: grad_phi_ges[1].subs(x=x,z=z) if > grad_len.subs(x=x,z=z) < 7 else None] > > plot_vector_field(my_grad, (x,-1,1), (z,-1,1), color='blue', > plot_points=22, axes_labels=['$x$ in [m]','$z$ in [m]'],typeset='latex', > frame=True, axes=False).save('vektorplot_gradient.png') > > and when executing that last line sage goes off and does not come back. > when pressing Ctrl-C after a while i got this traceback. perhaps you can > tell me what is wrong and how i could avoid it? > > please find attached also the file that i source in the beginning. > > > ^C--------------------------------------------------------------------------- > RuntimeError Traceback (most recent call last) > <ipython-input-1-9f045102c5a2> in <module>() > ----> 1 load('contour-und-vektor-plot.sage') > > /usr/lib/python2.7/dist-packages/sage/misc/persist.pyx in > sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2471)() > 134 > 135 if sage.repl.load.is_loadable_filename(filename): > --> 136 sage.repl.load.load(filename, globals()) > 137 return > 138 > > /usr/lib/python2.7/dist-packages/sage/repl/load.pyc in load(filename, > globals, attach) > 261 add_attached_file(fpath) > 262 with open(fpath) as f: > --> 263 exec(preparse_file(f.read()) + "\n", globals) > 264 elif ext == '.spyx' or ext == '.pyx': > 265 if attach: > > <string> in <module>() > > /usr/lib/python2.7/dist-packages/sage/misc/decorators.pyc in > wrapper(*args, **kwds) > 490 options['__original_opts'] = kwds > 491 options.update(kwds) > --> 492 return func(*args, **options) > 493 > 494 #Add the options specified by @options to the signature of > the wrapped > > /usr/lib/python2.7/dist-packages/sage/plot/plot_field.pyc in > plot_vector_field(f_g, xrange, yrange, **options) > 269 xpos_array.append(x) > 270 ypos_array.append(y) > --> 271 xvec_array.append(f(x, y)) > 272 yvec_array.append(g(x, y)) > 273 > > <string> in <lambda>(x, z) > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression.__nonzero__ > (build/cythonized/sage/symbolic/expression.cpp:19262)() > 2884 if pynac_result == relational_notimplemented and > self.operator()==operator.ne: > 2885 return not > (self.lhs()-self.rhs()).is_trivial_zero() > -> 2886 res = self.test_relation() > 2887 if res is True: > 2888 return True > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression.test_relation > (build/cythonized/sage/symbolic/expression.cpp:19878)() > 2993 if domain is None: > 2994 is_interval = True > -> 2995 if self.lhs().is_algebraic() and > self.rhs().is_algebraic(): > 2996 if op == equal or op == not_equal: > 2997 domain = QQbar > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression.is_algebraic > (build/cythonized/sage/symbolic/expression.cpp:15061)() > 2009 """ > 2010 try: > -> 2011 ex = sage.rings.all.QQbar(self) > 2012 except (TypeError, ValueError, NotImplementedError): > 2013 return False > > /usr/lib/python2.7/dist-packages/sage/structure/parent.pyx in > sage.structure.parent.Parent.__call__ > (build/cythonized/sage/structure/parent.c:9238)() > 887 if mor is not None: > 888 if no_extra_args: > --> 889 return mor._call_(x) > 890 else: > 891 return mor._call_with_args(x, args, kwds) > > /usr/lib/python2.7/dist-packages/sage/structure/coerce_maps.pyx in > sage.structure.coerce_maps.DefaultConvertMap_unique._call_ > (build/cythonized/sage/structure/coerce_maps.c:4659)() > 160 print(type(C), C) > 161 print(type(C._element_constructor), > C._element_constructor) > --> 162 raise > 163 > 164 cpdef Element _call_with_args(self, x, args=(), kwds={}): > > /usr/lib/python2.7/dist-packages/sage/structure/coerce_maps.pyx in > sage.structure.coerce_maps.DefaultConvertMap_unique._call_ > (build/cythonized/sage/structure/coerce_maps.c:4551)() > 155 cdef Parent C = self._codomain > 156 try: > --> 157 return C._element_constructor(x) > 158 except Exception: > 159 if print_warnings: > > /usr/lib/python2.7/dist-packages/sage/rings/qqbar.pyc in > _element_constructor_(self, x) > 1162 return AlgebraicNumber(x._descr) > 1163 elif hasattr(x, '_algebraic_'): > -> 1164 return x._algebraic_(QQbar) > 1165 return AlgebraicNumber(x) > 1166 > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression._algebraic_ > (build/cythonized/sage/symbolic/expression.cpp:11757)() > 1510 """ > 1511 from sage.symbolic.expression_conversions import algebraic > -> 1512 return algebraic(self, field) > 1513 > 1514 def __hash__(self): > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in algebraic(ex, field) > 1140 0 > 1141 """ > -> 1142 return AlgebraicConverter(field)(ex) > 1143 > 1144 ############## > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in __call__(self, ex) > 215 div = self.get_fake_div(ex) > 216 return self.arithmetic(div, div.operator()) > --> 217 return self.arithmetic(ex, operator) > 218 elif operator in relation_operators: > 219 return self.relation(ex, operator) > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in arithmetic(self, ex, operator) > 986 elif operator is mul_vararg: > 987 operator = _operator.mul > --> 988 return reduce(operator, map(self, ex.operands())) > 989 except TypeError: > 990 pass > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in __call__(self, ex) > 215 div = self.get_fake_div(ex) > 216 return self.arithmetic(div, div.operator()) > --> 217 return self.arithmetic(ex, operator) > 218 elif operator in relation_operators: > 219 return self.relation(ex, operator) > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in arithmetic(self, ex, operator) > 978 from sage.rings.all import Rational > 979 base, expt = ex.operands() > --> 980 base = self.field(base) > 981 expt = Rational(expt) > 982 return self.field(base**expt) > > /usr/lib/python2.7/dist-packages/sage/structure/parent.pyx in > sage.structure.parent.Parent.__call__ > (build/cythonized/sage/structure/parent.c:9238)() > 887 if mor is not None: > 888 if no_extra_args: > --> 889 return mor._call_(x) > 890 else: > 891 return mor._call_with_args(x, args, kwds) > > /usr/lib/python2.7/dist-packages/sage/structure/coerce_maps.pyx in > sage.structure.coerce_maps.DefaultConvertMap_unique._call_ > (build/cythonized/sage/structure/coerce_maps.c:4659)() > 160 print(type(C), C) > 161 print(type(C._element_constructor), > C._element_constructor) > --> 162 raise > 163 > 164 cpdef Element _call_with_args(self, x, args=(), kwds={}): > > /usr/lib/python2.7/dist-packages/sage/structure/coerce_maps.pyx in > sage.structure.coerce_maps.DefaultConvertMap_unique._call_ > (build/cythonized/sage/structure/coerce_maps.c:4551)() > 155 cdef Parent C = self._codomain > 156 try: > --> 157 return C._element_constructor(x) > 158 except Exception: > 159 if print_warnings: > > /usr/lib/python2.7/dist-packages/sage/rings/qqbar.pyc in > _element_constructor_(self, x) > 1162 return AlgebraicNumber(x._descr) > 1163 elif hasattr(x, '_algebraic_'): > -> 1164 return x._algebraic_(QQbar) > 1165 return AlgebraicNumber(x) > 1166 > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression._algebraic_ > (build/cythonized/sage/symbolic/expression.cpp:11757)() > 1510 """ > 1511 from sage.symbolic.expression_conversions import algebraic > -> 1512 return algebraic(self, field) > 1513 > 1514 def __hash__(self): > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in algebraic(ex, field) > 1140 0 > 1141 """ > -> 1142 return AlgebraicConverter(field)(ex) > 1143 > 1144 ############## > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in __call__(self, ex) > 215 div = self.get_fake_div(ex) > 216 return self.arithmetic(div, div.operator()) > --> 217 return self.arithmetic(ex, operator) > 218 elif operator in relation_operators: > 219 return self.relation(ex, operator) > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in arithmetic(self, ex, operator) > 986 elif operator is mul_vararg: > 987 operator = _operator.mul > --> 988 return reduce(operator, map(self, ex.operands())) > 989 except TypeError: > 990 pass > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in __call__(self, ex) > 215 div = self.get_fake_div(ex) > 216 return self.arithmetic(div, div.operator()) > --> 217 return self.arithmetic(ex, operator) > 218 elif operator in relation_operators: > 219 return self.relation(ex, operator) > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression_conversions.pyc > in arithmetic(self, ex, operator) > 993 from sage.symbolic.constants import e, pi, I > 994 base, expt = ex.operands() > --> 995 if base == e and expt / (pi*I) in QQ: > 996 return exp(expt)._algebraic_(self.field) > 997 > > /usr/lib/python2.7/dist-packages/sage/symbolic/expression.pyx in > sage.symbolic.expression.Expression.__nonzero__ > (build/cythonized/sage/symbolic/expression.cpp:19379)() > 2897 # lot of basic Sage objects can't be put into maxima. > 2898 from sage.symbolic.relation import test_relation_maxima > -> 2899 return test_relation_maxima(self) > 2900 > 2901 self_is_zero = self._gobj.is_zero() > > /usr/lib/python2.7/dist-packages/sage/symbolic/relation.pyc in > test_relation_maxima(relation) > 500 if relation.operator() == operator.eq: # operator is equality > 501 try: > --> 502 s = m.parent()._eval_line('is > (equal(%s,%s))'%(repr(m.lhs()),repr(m.rhs()))) > 503 except TypeError: > 504 raise ValueError("unable to evaluate the predicate > '%s'" % repr(relation)) > > /usr/lib/python2.7/dist-packages/sage/interfaces/maxima_lib.pyc in > _eval_line(self, line, locals, reformat, **kwds) > 454 line = line[ind_semi+1:] > 455 if statement: > --> 456 result = ((result + '\n') if result else '') + > max_to_string(maxima_eval("#$%s$"%statement)) > 457 else: > 458 statement = line[:ind_dollar] > > /usr/lib/python2.7/dist-packages/sage/libs/ecl.pyx in > sage.libs.ecl.EclObject.__call__ (build/cythonized/sage/libs/ecl.c:7937)() > 818 """ > 819 lispargs = EclObject(list(args)) > --> 820 return > ecl_wrap(ecl_safe_apply(self.obj,(<EclObject>lispargs).obj)) > 821 > 822 def __richcmp__(left, right, int op): > > /usr/lib/python2.7/dist-packages/sage/libs/ecl.pyx in > sage.libs.ecl.ecl_safe_apply (build/cythonized/sage/libs/ecl.c:5599)() > 390 if ecl_nvalues > 1: > 391 s = si_coerce_to_base_string(ecl_values(1)) > --> 392 raise RuntimeError("ECL says: {}".format( > 393 char_to_str(ecl_base_string_pointer_safe(s)))) > 394 else: > > RuntimeError: ECL says: Console interrupt. > > -- You received this message because you are subscribed to the Google Groups "sage-support" group. 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