### Parallel Interface to the Sage interpreter

I am using the `PSage()`

parallel interpreter as described here http://doc.sagemath.org/html/en/reference/interfaces/sage/interfaces/psage.html#sage-interfaces-psage. The interface works fine to evaluate multiple instances of function calls to functions of one or more scalar variables, however, if a function variable is array-like, the interface doesn't seem to work any more. I wonder if any special quoting is necessary for array-like arguments. Here is a minimal example. For reference, I copy the example from the above page, which works just fine, `factor()`

has a single scalar variable.

```
v = [PSage() for _ in range(3)]
w = [x('factor(2^%s-1)'% randint(250,310)) for x in v]
w
[4057 * 8191 * 6740339310641 * 3340762283952395329506327023033,
31 * 13367 * 2940521 * 164511353 * 70171342151 *
3655725065508797181674078959681,
31 * 13367 * 2940521 * 164511353 * 70171342151 *
3655725065508797181674078959681]
```

However, the `rosen()`

function with a single array-like/vector argument doesn't seem to work in the parallel interface. (The example below just calculates the same function value three times, but that is not the point here.)

```
from scipy.optimize import rosen
x0 = [1.3, 0.7, 0.8, 1.9, 1.2]
rosen(x0)
848.22000000000003
v = [PSage() for _ in range(3)]
w = [x('rosen(x0)') for x in v]
w
[Sage, Sage, Sage]
```

Does anyone have any suggestion?