Re: what is the use of "u" in tabulated output?

[<pl...@pi...>]

On 04/20/14 10:48, pl...@pi... wrote:
>
>    HI,
>
>
> I often use conditional using clauses to plot part of a range of data
>
> plot datafile using   (($1<=1995.55)?$1:NaN):(2*fcos1($1))
>
> I tried this when writing to a file specified with "set table"  and
> instead of cutting off the output, it appends garbage data with a "u".
>
> help table tells me this means "undefined"
>
> I see two problems here. I did not ask for undefined output , I
> specified NaN.
>
> Secondly , what is the possible use of "undefined" values in a data file?
>
> 1995.46  1.00914  i
> 1995.54  1.10947  i
> 1.98547e-81  4.74363e+170  u
> 3.75845e+174  7.52884e-24  u
> 0  2.122e-314  u
> 0  0  u
> 0  0  u
> 1.9771e+161  1.44402e+214  u
> -1.22337e-44  1.1735e-319  u
> 1.01887e+189  7.49746e+247  u
> 5.35166e+199  2.10124e+88  u
>
>
>   From my using clause I would expect either
>
> NaN [ correct value of 2*fcos($1) ] o
> NaN [ correct value of 2*fcos($1) ] i
>
> or preferable nothing at all , as would reflect the usual terminal
> output for NaN points.
>
>    Version 4.7 patchlevel 0    last modified 2012-10-16
>           Build System: Linux i686
>
>
>
> Thanks , Peter
>


I've just found out the if I used "NaN" as a string instead of NaN in 
the using clause I get the result I expected: the data cuts off at the 
required date.

plot datafile using   (($1<=1995.55)?$1:"NaN"):(2*fcos1($1))

It seems there is an inconsistency in the way this is being handled. 
Clearly I should not need two different versions of the plot command.

Peter.