# assertion error

Sage gave me the message

```
Traceback (most recent call last): print'%4s %4s %4s %4s %4s %4s %4s %4s'%(a,b,c,d,p,Nr(a,b,c,d,p),z1.subs(a=a,b=b,c=c,d=d,p=p),Nz1.subs(a=a,b=b,c=c,d=d,p=p))
File "", line 1, in <module>
File "/tmp/tmpyutrvn/___code___.py", line 3, in <module>
exec compile(u"for a in im:\n for b in range(_sage_const_16 ):\n for c in range(_sage_const_16 ):\n for d in range(_sage_const_16 ):\n for p in ps2:\n if Nr(a,b,c,d,p)%_sage_const_16 ==_sage_const_2 and (H1.subs(a=a,b=b,c=c,d=d,p=p)).denominator()==_sage_const_1 and H1.subs(a=a,b=b,c=c,d=d,p=p)%_sage_const_8 ==_sage_const_1 :\n print'%4s %4s %4s %4s %4s %4s %4s %4s'%(a,b,c,d,p,Nr(a,b,c,d,p),z1.subs(a=a,b=b,c=c,d=d,p=p),Nz1.subs(a=a,b=b,c=c,d=d,p=p))" + '\n', '', 'single')
File "", line 6, in <module>
File "expression.pyx", line 6324, in sage.symbolic.expression.Expression.denominator (sage/symbolic/expression.cpp:24114)
File "expression.pyx", line 448, in sage.symbolic.expression.Expression._maxima_ (sage/symbolic/expression.cpp:3674)
File "sage_object.pyx", line 439, in sage.structure.sage_object.SageObject._interface_ (sage/structure/sage_object.c:3622)
File "/home/pquiroz/Escritorio/sage-4.7-linux-64bit-ubuntu_10.04.1_lts-x86_64-Linux/local/lib/python2.6/site-packages/sage/interfaces/expect.py", line 1105, in __call__
return cls(self, x, name=name)
File "/home/pquiroz/Escritorio/sage-4.7-linux-64bit-ubuntu_10.04.1_lts-x86_64-Linux/local/lib/python2.6/site-packages/sage/interfaces/expect.py", line 1535, in __init__
self._name = parent._create(value, name=name)
File "/home/pquiroz/Escritorio/sage-4.7-linux-64bit-ubuntu_10.04.1_lts-x86_64-Linux/local/lib/python2.6/site-packages/sage/interfaces/expect.py", line 1294, in _create
self.set(name, value)
File "/home/pquiroz/Escritorio/sage-4.7-linux-64bit-ubuntu_10.04.1_lts-x86_64-Linux/local/lib/python2.6/site-packages/sage/interfaces/maxima.py", line 1200, in set
self._eval_line(cmd)
File "/home/pquiroz/Escritorio/sage-4.7-linux-64bit-ubuntu_10.04.1_lts-x86_64-Linux/local/lib/python2.6/site-packages/sage/interfaces/maxima.py", line 759, in _eval_line
assert line_echo.strip() == line.strip()
AssertionError
```

I don't understand what is happening here and how to solve it.

Hi @Pato! Can you give us a full set of input code and edit your question so that we can see the *input* which caused this error? As it stands, this is pretty hard to figure out, though the proximate cause was that we tried to evaluate some integral in Maxima and apparently it didn't look the same when printed as when input, somehow. At any rate, this should raise a more helpful error... so please let us know!