From: Ashar Malik (asharjm_at_gmail.com)
Date: Sat Jan 17 2015 - 05:01:53 CST

I would disagree with that.

here is why:

This is in the pdb:
71.696 112.940 -84.327

after using the code the output is:

{71.69599914550781 112.94000244140625 -84.3270034790039}

If you observe the x-coordinates -- 71.696 is in the PDB which is being
read into TCL by the script i sent earlier and it shows 71.695999 .,.. that
means that PDB TEXT file was displaying a rounded off number. Where as --
somehow when the TCL script read the PDB TEXT file ... it produced --
71.69599.. which is the un-rounded off number.

On Sat, Jan 17, 2015 at 11:23 PM, Michail Palaiokostas Avramidis <
m.palaiokostas_at_qmul.ac.uk> wrote:

> Hi Ashar,
>
> I think that a coordinate is stored as a double precision number in the
> memory. However the PDB file contains only a fraction of a double number's
> decimals. Therefore the rest are filled with what the memory had before. If
> it is important for you to have zero's in that level, I suppose you can
> find a way to initialize the variables in a way that gives 0 for all digits.
>
> Hope that helps.
>
> Best,
> Michail Palaiokostas
>
>
> ---- Ashar Malik wrote ----
>
>
> Hi,
>
> The coordinates in the PDB file of an atom are:
>
> 75.146 114.983 -86.817
>
> using
>
> for {set i $first} {$i < $last} {incr i} {
> set sel3 [atomselect top "resid $i and name C1'"]
> puts [$sel3 get {x y z}]
> }
>
> they are returned as:
>
> {75.14600372314453 114.98300170898438 -86.81700134277344}
>
> Question:
>
> Maybe I am missing some understanding of something here:
>
> How does VMD/TCL script get the higher precision??
>
> Any comments anyone ??
>
> --
> Best,
> /A
>

-- 
Best,
/A