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Oddity in root involving erf

TomGutman
Newbie

Oddity in root involving erf

Another oddity in the symboic processor, at least in 2001i. This is particularly odd, as officially (in the help) erf is not even defined for complex values. Also another case where the symbolic processor has switched to a numeric float evaluation even though there is nothing in the original expression that should trigger that.

Tom Gutman
3 REPLIES 3

Oddity in root involving erf

On 9/24/2003 5:47:04 PM, Tom_Gutman wrote:
>Another oddity in the symboic
>processor, at least in 2001i.
>This is particularly odd, as
>officially (in the help) erf
>is not even defined for
>complex values. Also another
>case where the symbolic
>processor has switched to a
>numeric float evaluation even
>though there is nothing in the
>original expression that
>should trigger that.
>
>Tom Gutman
_____________________________

One more ugly bug !

Either a bug or something we don't understand.
Even if the result has an explanation, it deserves a message, otherwise the user can do wrong or is left confused.
Very nice you persist. We had reported many more in the past, but none (to my recollection) were answered.


Oddity in root involving erf

Tom,

Mathcad does not have the InverseErf(x).
No problem, we find at point using root.

If a continuous function like in Mathematica is of interest to you, here is the series expansion.
Unfortunately Mathcad fails the series ... why ?

In Mathcad 8, I made the Thiele approximation for
InverseErf(x).
Today, I have a lot more expertise in Thiele. I could remake it with greater accuracy.

Let me know. I may try tonight

jmG

Oddity in root involving erf

No, I don't really need the general inverse. I was specifically interested in that point, and the numeric solver finds it easily enough. I just thought the symbolic solver's opinion sufficiently weird to merit some attention.

Tom Gutman
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