Re: NaN and missing values

[heberf]

Yes, that would do it.  We would also need a load command which would interpret 
two data seperators (like TAB or commas for csv files) as a missing value.  
Another issue is how will the matrix X appear when you type X at the prompt.  
My 
recommendation would be that a missing value gets displayed as a  .  on the 
screen.  This seems to be more or less standard.

Heber

> On 23-Sep-1999, heberf <address@hidden> wrote:
> 
> | Would NaN be an acceptable code [to indicate missing data] or do we
> | need another?
> 
> Overloading NaN to mean `missing data' seems wrong to me, because NaNs
> can be generated for other reasons too, and if you just see a NaN,
> there would be no way to tell if it came from a calculation or because
> it was intended to fill the location of a missting datum.
> 
> I think the right solution is to create a (set of) new numeric data
> type(s) that can also have markers for missing data.  One possible
> implementation for a matrix with missing values would be to use the
> Matrix data type but also add an additional vector (or matrix) to mark
> the locations of missing data.  Any functions that need to work with
> this new data type would have to be modified to use it.  Functions not
> modified to work with it would just signal `wrong type' errors.
> 
> jwe
> 
> 
> 
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