### Conversion between RealField

I found the following behaviour very unintuitive :

```
R128=RealField(128)
pi_r128=R128.pi()
print pi_r128*2
print pi_r128*2.
print RR(pi)*2
```

The corresponding output is :

```
6.2831853071795864769252867665590057684
6.28318530717959
6.28318530717959
```

The first line was the expected behavior.

The second line was not expected because floating number **2.** has the default precision contrary to **pi_r128** whose is precision is wider. As the 3rd line shows, the 128 bit precision is completely ignored from **pi_r128*2** calculation.

So I was wondering how conversion between RealField numbers was done.