Issues with Latex Rendering

[Tony Saad]

Sometimes strange looking modified equations show up with terms that do not multiply a derivative.
This is an example from James.
`from sympy import symbols,latex
from src.pymodpde import DifferentialEquation, i, n

u= symbols('u')
D= symbols('D')

pde = DifferentialEquation( dependentVarName='y',
independentVarsNames=['x'])

t = n+1
advection = ( pde.y(time=t,x=i) - pde.y(time=t,x=i-1) ) / (pde.dx)
diffusion = ( pde.y(time=t,x=i-1)
- 2*pde.y(time=t,x=i)
+ pde.y(time=t,x=i+1)
) / pde.dx**2

pde.set_rhs( (-uadvection) + (Ddiffusion ))

pde.generate_amp_factor()
pde.display_amp_factor()
pde.generate_modified_equation(nterms=3)
pde.display_modified_equation()One potential solution is to usesymbolic_modified_equation()instead ofdisplay_modified_equation` until the latter is fixed

[James Sutherland]

Duplicate of #23