[GRASS5] Re: r.in.gdal - precision problem in lib/gis/adj_cellhd.c

[Hamish]

> > > I have noticed in the past that v.out.ogr to a shapefile does
> > > similar strange off-by 1e-9 type errors to double precision columns
> > > in the data.
> > 
> > Mhh, a systematic problem?
> 
> 
> No I think it is probably separate but wanted to note. A double cast to
> float and then back to double introducing some noise?


example:

G6> echo "1.0|2.0|10.2" | v.in.ascii out=ogr_testG
...
column: 1  type: double
column: 2  type: double
column: 3  type: double
...

G6> dbview -bt $MAPSET/dbf/ogr_testG.dbf
1:1.000000:2.000000:10.200000:

[db.describe output below]


G6> v.out.ogr input=ogr_testG type=point dsn=. olayer=ogr_testS

G6> dbview -bt ogr_testS.dbf
1:1.000000000000000:2.000000000000000:10.199999999999999:




Hamish





G6> db.describe ogr_testG
table:ogr_testG
description:
insert:yes
delete:yes
ncols:4

column:cat
description:
type:INTEGER
len:11
scale:0
precision:10
default:0
nullok:yes
select:yes
update:yes

column:dbl_1
description:
type:DOUBLE PRECISION
len:20
scale:6
precision:18
default:0
nullok:yes
select:yes
update:yes

column:dbl_2
description:
type:DOUBLE PRECISION
len:20
scale:6
precision:18
default:0
nullok:yes
select:yes
update:yes

column:dbl_3
description:
type:DOUBLE PRECISION
len:20
scale:6
precision:18
default:0
nullok:yes
select:yes
update:yes