There was a bug in the pow function, that affected your code, which is fixed in v6.2.1805, if you update it should work. (if you build from source, you need to check out after this fix:
github.com/NGSolve/ngsolve/commit/764a27...e58ace6086563a2a044e
)
Note as well, that the linearform is built outside the loop and only reassembled inside, this saves the time to allocate/deallocate the vectors. Your version should work as well, but is less efficient.
Code:
from ngsolve import *
import math
from netgen.geom2d import unit_square
from time import sleep
gamma = 0.1
mesh = Mesh(unit_square.GenerateMesh(maxh=0.2))
fes = H1(mesh,order=2)
v = fes.TestFunction()
t = Parameter(0)
gausspt = (1 - t + ((math.pi)**2)*(1-t+(1/2)*t**2 - (1/6)*t**3)
-(t**(gamma))/(math.gamma(1-gamma)) + (t**(1-gamma))/(math.gamma(2-gamma))
-(t**(2-gamma))/(math.gamma(3-gamma)))*sin(math.pi * x) *sin(math.pi *y)
Draw(gausspt,mesh,"gausspt")
time = 0
tend = 5
dt = 1e-2
ft = LinearForm(fes)
ft += SymbolicLFI(gausspt*v)
while time < tend-dt/2:
time +=dt
t.Set(time)
Redraw()
sleep(0.1)
ft.Assemble()
Best
Christopher
