Related Thread.

From: Paul Hutson 
Subject: [NMusers] Digital Visual Fortran vers 5.0 vs 6.6 and NM-TRAN Bug
Date: Tue, 19 Mar 2002 16:52:52 -0600

Nick's answer then prompts another question: Which results are better, and 
how would one tell?



Paul Hutson, Pharm.D.
Associate Professor (CHS)
UW School of Pharmacy
NOTE NEW ADDRESS effective 6/2001
777 Highland Avenue
Madison, WI 53705-2222
Tel:    (608) 263-2496
FAX:    (608) 265-5421
Pager: (608) 265-7000, #7856





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From:  Nick Holford 
Subject:  Re: [NMusers] Digital Visual Fortran vers 5.0 vs 6.6
Date: Wed, 20 Mar 2002 13:04:21 +1200

Paul Hutson wrote:

My answer is in two parts. First of all I found a bug in NM-TRAN.
The bug produces a TIME item in FDATA with inconsistent format and causes data truncation.

One kind of data set structure produces FDATA that is E7.0 for TIME whereas changes in data items produces
a format of E8.0 for TIME.
e.g.
FDATA
  96 112 1173.05164.271              986.08  14.08 64  2 89  1  1
(E1.0,E3.0,E4.0,E7.0,E1.0,E6.0,E1.0,E6.0,2E2.0,3E1.0,2E7.0,5E3.0) 

TIME is 1173.0 in data item 4.

Changing the structure of the data set (but not the values used by the model) e.g. by dropping one or more
items so that there are fewer data items preserves an additional digit of precision for TIME:
FDATA 
      96     112 1173.08       5  164.27       1                        
                          986.08   14.08      64       2      89       1
(2(9E8.0/),1E8.0)

TIME is 1173.08 in data item 4.

I would like to submit details of the data to Globomax so that they can investigate and fix the NM-TRAN
bug. I am waiting for a reply from the owner of the data so I can send it to Globomax. Hint to Dr XX at the
YYY company to please reply!

Now for the second part which relies on these small differences being produced by the NM-TRAN bug.
Here are results showing OBJ and SigDig with 3 DF compiler versions using the truncated and full precision
values for TIME created by the NM-TRAN bug:

Data    Version OBJ             SigDig
Trunc   6.6     20067.293       2.7
Full    6.6     20089.472       2.5
Trunc   6.5     20100.58        .
Full    6.5     20096.119       2.6
Trunc   6.0A    20091.387       3.4
Full    6.0A    20091.676       2.9

NONMEM was compiled for all 3 versions with these options /fltconsistency /optimize:4 /fast.
DF 6.0A gets essentially the same OBJ. DF 6.5 has higher OBJ for both data sets but can tell them apart. DF
6.6 has 22 unit lower OBJ with the trunc vs full data sets and both OBJ values are lower than with the
earlier versions. 

So I would conclude that DF 6.6 is more sensitive to small differences in the data and can get to a lower
objective function. These differences suggest that this is because of better numerical precision using DF
6.6.

Does anyone have a plausible alternative explanation?

Nick

-- 
Nick Holford, Divn Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand
email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556
http://www.health.auckland.ac.nz/pharmacology/staff/nholford/


*******


From: "Ludden, Thomas" 
Subject: RE: [NMusers] Digital Visual Fortran vers 5.0 vs 6.6
Date: Wed, 20 Mar 2002 09:27:34 -0500

Nick has confirmed that the WIDE option on the $DATA record prevents the
data truncation that he has observed.  Please see the documentation for this
option under $DATA in Guide VIII for additional details.

Tom Ludden


-----Original Message-----
From: Nick Holford [mailto:n.holford@auckland.ac.nz]
Sent: Tuesday, March 19, 2002 8:26 PM
To: Bachman, William
Subject: Re: try the WIDE option to see if it prevents the truncation.


Bill,

The WIDE option does indeed prevent the truncation. But its still an NM-TRAN
bug when the default NOWIDE option is used :-(

Nick

*******


From: "Sam Liao" 
Subject: RE: [NMusers] Digital Visual Fortran vers 5.0 vs 6.6
Date: Wed, 20 Mar 2002 11:56:48 -0500

Nick:

Thanks alot for the info about DF 6.6.  I am debating whether I should rush
to the store to get the DF compiler upgraded.  I hope the survey Dr. Peter
Bonate is conducting will provide some good answer for us.

There is still 10 more days for NONMEM users to submit their results of the
part one consistency test to Peter.


Sam Liao, Ph.D.
PharMax Research
270 Kerry Lane,
Blue Bell, PA 19422
phone: 215-654115


*******

From: "Venkatesh Atul Bhattaram" 
Subject: Re: [NMusers] Digital Visual Fortran vers 5.0 vs 6.6
Date: Wed, 20 Mar 2002 13:21:46 -0500

Hello All

I did one analysis comparison between Fortran Power Station (Ver4.0) and
Compaq Visual Fortran (Ver 6.6) using a data set in which I had 2460
observed records from 156 individuals on Win2000. I used a simple FO for the
analysis. In both cases the final results (parameter estimates) were almost
identical.  The number of functions evaluations were 602 (VF6.6) and 561
(Power Station). The number of significant digits were 3.2 (VF6.6) and 3.3
(Power Station). I am not sure with other intensive procedures like FOCE
etc.

Venkatesh Atul Bhattaram
Post-doctoral Fellow
University of Florida


*******


From: "Diane R Mould" 
Subject: RE: [NMusers] Digital Visual Fortran vers 5.0 vs. 6.6
Date: Thu, 21 Mar 2002 08:37:32 -0500

Dear All

Its probably worth noting that the WIDE option can not be used if the data
set is very large (more than 9999 rows of data).  I just tried using it on a
rather large data set and got the following error:

283  $DATA: WIDE CANNOT BE USED - FILE CONTAINS MORE THAN 9999 RECS.
Error in nmtran

Best Regards
Diane

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Related thread for NM-TRAN Bug