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[Bento <771259@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

I try to solve a time-dependent problem, however the plotting does not show the change of the function over time. The plot window always shows the function in that timestep in which the plot command was first called. What am I doing wrong? The time-dependent example look similar, but they work.
Here is the simplest example that goes wrong:

from dolfin import *

T_initial = Constant(293.0)

dt = 1.0
t = dt

mesh = Interval(200, 0, 20.0)

V = FunctionSpace(mesh, "CG", 1)

T = TrialFunction(V)
v = TestFunction(V)

def inflow(x, on_boundary):
    return on_boundary and x[0] < 1.0
    
BC = DirichletBC(V, 800.0, inflow)
T_prev = interpolate(T_initial, V)

a = (T*v + dt*T.dx(0)*v.dx(0))*dx
L = T_prev*v*dx

f = Function(V)


while t < 1000:
    A = assemble(a)
    l = assemble(L)
    BC.apply(A,l)
    solve(A,f.vector(), l)
    plot(f)
    T_prev.assign(f)
    t += dt

Using mesh = Rectangle(0,0,20,1, 200, 1) instead works fine.

** Affects: dolfin
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/771259

Title:
  Viper fails to plot one-dim time dependent functions

Status in DOLFIN:
  New

Bug description:
  I try to solve a time-dependent problem, however the plotting does not show the change of the function over time. The plot window always shows the function in that timestep in which the plot command was first called. What am I doing wrong? The time-dependent example look similar, but they work.
  Here is the simplest example that goes wrong:

  from dolfin import *

  T_initial = Constant(293.0)

  dt = 1.0
  t = dt

  mesh = Interval(200, 0, 20.0)

  V = FunctionSpace(mesh, "CG", 1)

  T = TrialFunction(V)
  v = TestFunction(V)

  def inflow(x, on_boundary):
      return on_boundary and x[0] < 1.0
      
  BC = DirichletBC(V, 800.0, inflow)
  T_prev = interpolate(T_initial, V)

  a = (T*v + dt*T.dx(0)*v.dx(0))*dx
  L = T_prev*v*dx

  f = Function(V)

  
  while t < 1000:
      A = assemble(a)
      l = assemble(L)
      BC.apply(A,l)
      solve(A,f.vector(), l)
      plot(f)
      T_prev.assign(f)
      t += dt

  Using mesh = Rectangle(0,0,20,1, 200, 1) instead works fine.