Ternary operator in expression

Question

Hi. My code work fine in Windows. But in ubuntu 13.04 i have problem with

S = Expression('(x[0]<1)?0.1/(0.5*t*t+1):0.0',t=0.0)

Problem in ternary operator.

In instant.recompile: The module did not compile with command 'make VERBOSE=1 ', see '/home/sheva/.instant/error/dolfin_compile_code_42d1ae0f370daad6abfc317bff5c25ea/compile.log'
Traceback (most recent call last):
  File "fallout_4d.py", line 45, in <module>
    S = Expression('(x[0]<1)?0.1/(0.5*t*t+1):0.0',t=0.0)

Without ternary operator code work fine.
Fenics Win version 1.0 and python 2.3.5, ubuntu 13.04 have latest version of fenics and python 2.7.4.

Comments

You should check "/home/sheva/.instant/error/dolfin_compile_code_42d1ae0f370daad6abfc317bff5c25ea/compile.log" and ask again (including the error messages) if it's still unclear.

Answer 1

Hi, I think your problem is related to spacing. I have the same version of python, Ubuntu and FEniCS as you do and your code does not compile on my machine either. However

S = Expression('(x[0]<1) ? 0.1/(0.5*t*t+1) : 0.0',t=0.0) 

is okay and so is

S = Expression('(x[0]<1)?0.1/(0.5*t*t+1) : 0.0',t=0.0)

(note spaces around colon) or

S = Expression('(x[0]<1)?0.1/(0.5*t*t+1): 0.0',t=0.0)

(note only the trailing space after colon). Finally

S = Expression('(x[0]<1)?0.1/(0.5*t*t+1) :0.0',t=0.0)

(note only the leading space) fails to compile.