1 | initial version |

This is something relatively new to Sage, via Maxima. See this Maxima devel post for details.

What this means is that we have yet to implement this conversion in Sage - not surprising, since it doesn't seem to be in Ginac. (In fact, erf doesn't even seem to be in Ginac!)

However, it *is* in mpmath.

```
sage: e^(sqrt(2)*RR(mpmath.erfinv(1/2))).n()
1.96303108415826
```

Unfortunately, it was *extremely* difficult to get this to work right. There are two things we need to do for this.

- Have a symbolic inverse erf function, which we do not yet have.
Make a

`._sage_()`

method for mpmath numbers, or make it easier to figure out how to get them symbolic. There is also no`.n()`

method. I shouldn't have to to this if I forget`RR`

!sage: e^(sqrt(2)*sage.libs.mpmath.all.mpmath_to_sage(mpmath.erfinv(1/2),53)).n()

1.96303108415826

This reminds me that askbot has still not fixed the issue of formatting after bullets (which, to be fair, was upstream from them...)

2 | No.2 Revision |

This is something relatively new to Sage, via Maxima. See this Maxima devel post for details.

What this means is that we have yet to implement this conversion in Sage - not surprising, since it doesn't seem to be in Ginac. (In fact, erf doesn't even seem to be in Ginac!)

However, it *is* in mpmath.

```
sage: e^(sqrt(2)*RR(mpmath.erfinv(1/2))).n()
1.96303108415826
```

Unfortunately, ~~it was ~~the typical beginning user might not know the *extremely* difficult to get this to work right. `RR`

trick. There are two things we need to do for this.

- Have a symbolic inverse erf function, which we do not yet have.
Make a

`._sage_()`

method for mpmath numbers, or make it easier to figure out how to get them symbolic. There is also no`.n()`

method. I shouldn't have to to this if I forget`RR`

!sage: e^(sqrt(2)*sage.libs.mpmath.all.mpmath_to_sage(mpmath.erfinv(1/2),53)).n()

1.96303108415826

This reminds me that askbot has still not fixed the issue of formatting after bullets (which, to be fair, was upstream from them...)

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