# Problem with partial fraction's decomposition

I’m trying to do a partial fraction decomposition using respectively x, and k as variable and parameter. Running on sagemath there’s a problem. The code is

```
x, k=var('x','k');
f1=1;
f2=k^2 - x^2;
f12=f1/f2;
f=f12(x).partial_fraction();
fi = integral(f12,x);
print (latex(f));
print (latex(fi));
```

and the message:

```
ValueError: power::eval(): division by zero.
```

Probably I have to assume that f2 not equal to 0, but how. Any help?