[ferret_users] data size estimation is not unique

[Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx>]

Hi,
reading ascii data, I encountered the following problem. The estimated 
length of an input field depends on the history of operations.
 
My data file test.data looks like this
 
header
1, 1
2, 2
3, 3
 
The script to read the data and to estimate the length of the field is
 
set data/ez/skip=1/var=t1,t2/format=delim/type=numeric test.data
let imax=`t1,return=iend`
list imax
 
ferret
NOAA/PMEL TMAP
PyFerret v7.22 (optimized)
Linux 4.4.87-25-default - 10/05/17
24-Oct-17 17:12
 
CAN MODE LOGO
SET MEM /SIZE=25.6
SET MODE VERIFY
yes? set data/ez/skip=1/var=t1,t2/format=delim/type=numeric test.data
yes? let imax=`t1,return=iend`
!-> DEFINE VARIABLE imax=4
yes? list imax
VARIABLE : 4
4.000
yes?
I would say, the result for imax is wrong.
 
Modifying the script, just by adding a 'list' command gives the correct 
(or a more likely) result:
yes? set data/ez/skip=1/var=t1,t2/format=delim/type=numeric test.data
yes? list t1
VARIABLE : t1
FILENAME : test.data
SUBSET : 3 points (X)
1 / 1: 1.000
2 / 2: 2.000
3 / 3: 3.000
yes? let imax=`t1,return=iend`
!-> DEFINE VARIABLE imax=3
yes? list imax
VARIABLE : 3
3.000
yes?
 
This dependence of the variable size estimate on the history of 
operations seems to be inherited over generations of ferret. I have very 
old scripts, where some 'list' or 'shade' was added to get them running.
 
May be, the report helps.
 
Best,
Martin
 
 
 
--
Dr. Martin Schmidt
Leibniz-Institute for Baltic Sea Research
Seestrasse 15
D18119 Rostock
Germany