NAG Fortran Library, Mark 20

FLDVV20DA

DEC VAX/VMS Double Precision

Users' Note



Contents


1. Introduction

This document is essential reading for every user of the NAG Fortran Library Implementation specified in the title. It provides implementation-specific detail that augments the information provided in the NAG Fortran Library Manual and Introductory Guide. Wherever those manuals refer to the "Users' Note for your implementation", you should consult this note.

In addition, NAG recommends that before calling any library routine you should read the following reference material (see Section 3.5 and Section 5):

(a) Essential Introduction
(b) Chapter Introduction
(c) Routine Document

The libraries supplied with this implementation have not been compiled in a manner that facilitates the use of multiple threads.

2. Availability of Routines

All routines listed in the chapter contents documents of the NAG Fortran Library Manual, Mark 20 are available in this implementation. At Mark 20, 95 new primary ("user-callable") routines and 36 thread safe equivalents of existing routines have been introduced. Two routines have been deleted. Please consult Mark 20 News (see Section 3.5 and Section 5) for lists of these routines and for a list of routines scheduled for withdrawal at Mark 21 or later. Your suggestions for new algorithms for future releases of the Library are welcomed (see Section 7).

3. General Information

3.1. Accessing the Library

To compile a Fortran program, type 
FORTRAN <program>
where <program> is the name of a .FOR file containing your program.

To link a program with the NAG Library, assuming that the library has been associated with a LNK$LIBRARY logical, type 

LINK <program>
where <program> is the name of a .OBJ file containing your compiled program.

To run the program, type 

ASSIGN <data>    FOR005
ASSIGN <results> FOR006
RUN    <program>
where <program> is the name of a .EXE file containing your linked program, <data> is data to be read from Fortran channel 5, and <results> are results to be written to Fortran channel 6.

3.2. Example Programs

In the NAG Fortran Library Manual, routine documents that have been typeset since Mark 12 present the example programs in a generalised form, using bold italicised terms as described in Section 3.3.

In other routine documents, the example programs are in single precision and require modification for use with double precision routines. This conversion can entail:

The example programs supplied to a site in machine-readable form have been modified as necessary so that they are suitable for immediate execution. Note that the distributed example programs are those used in this implementation and may not correspond exactly with the programs published in the manual. The distributed example programs should be used in preference wherever possible.

3.3. Interpretation of Bold Italicised Terms

For this double precision implementation, the bold italicised terms used in the NAG Fortran Library Manual should be interpreted as: 

real                 - DOUBLE PRECISION (REAL*8)
basic precision      - double precision
complex              - COMPLEX*16
additional precision - quadruple precision (REAL*16)
machine precision    - the machine precision, see the value
                       returned by X02AJF in Section 4

Thus a parameter described as real should be declared as DOUBLE PRECISION in your program. If a routine accumulates an inner product in additional precision, it is using software to simulate quadruple precision.

In routine documents that have been newly typeset since Mark 12 additional bold italicised terms are used in the published example programs and they must be interpreted as follows: 

real as an intrinsic function name - DBLE
imag                               - DIMAG
cmplx                              - DCMPLX
conjg                              - DCONJG
e in constants, e.g. 1.0e-4        - D, e.g. 1.0D-4
e in formats, e.g. e12.4           - D, e.g. D12.4

All references to routines in Chapter F07 - Linear Equations (LAPACK) and Chapter F08 - Least-squares and Eigenvalue Problems (LAPACK) use the LAPACK name, not the NAG F07/F08 name. The LAPACK name is precision dependent, and hence the name appears in a bold italicised typeface.

The typeset examples use the single precision form of the LAPACK name. To convert this name to its double precision form, change the first character either from S to D or C to Z as appropriate.
For example: 

sgetrf refers to the LAPACK routine name - DGETRF
cpotrs                                   - ZPOTRS

3.4. Explicit Output from NAG Routines

Certain routines produce explicit error messages and advisory messages via output units which either have default values or can be reset by using X04AAF for error messages and X04ABF for advisory messages. (The default values are given in Section 4). The maximum record lengths of error messages and advisory messages (including carriage control characters) are 80 characters, except where otherwise specified. These routines are potentially not thread safe and in general output is not recommended in a multithreaded environment.

3.5. User Documentation

The following machine-readable information files are provided:

See Section 5 for additional documentation available from NAG.

4. Routine-specific Information

Any further information which applies to one or more routines in this implementation is listed below, chapter by chapter.

(a) D03

The example programs for D03RAF and D03RBF take much longer to run than other examples.

(b) G02

The value of ACC, the machine-dependent constant mentioned in several documents in the chapter, is 1.0D-14.

(c) P01

On hard failure, P01ABF writes the error message to the error message unit specified by X04AAF and then stops.

(d) S07 - S21

The constants referred to in the NAG Fortran Library Manual have the following values in this implementation: 
S07AAF  F(1)   = 1.0D+15
        F(2)   = 1.0D-16
 
S10AAF  E(1)   = 20.75
S10ABF  E(1)   = 88.00
S10ACF  E(1)   = 88.00
 
S13AAF  x(hi)  = 88.02
S13ACF  x(hi)  = 1.0D+18
S13ADF  x(hi)  = 1.0D+19
 
S14AAF  IFAIL  = 1 if X > 33.0
        IFAIL  = 2 if X < -33.0
        IFAIL  = 3 if abs(X) < 5.88D-39
S14ABF  IFAIL  = 2 if X > 2.05D+36
 
S15ADF  x(hi)  = 9.38
        x(low) = -6.50
S15AEF  x(hi)  = 6.25
 
S17ACF  IFAIL  = 1 if X > 1.0D+16
S17ADF  IFAIL  = 1 if X > 1.0D+16
        IFAIL  = 3 if 0.0 < X <= 5.88D-39
S17AEF  IFAIL  = 1 if abs(X) > 1.0D+16
S17AFF  IFAIL  = 1 if abs(X) > 1.0D+16
S17AGF  IFAIL  = 1 if X > 25.52
        IFAIL  = 2 if X < -2.2D+11
S17AHF  IFAIL  = 1 if X > 25.93
        IFAIL  = 2 if X < -2.2D+11
S17AJF  IFAIL  = 1 if X > 25.84
        IFAIL  = 2 if X < -5.9D+09
S17AKF  IFAIL  = 1 if X > 25.93
        IFAIL  = 2 if X < -5.9D+09
S17DCF  IFAIL  = 2 if abs (Z) < 5.80D-36
        IFAIL  = 4 if abs (Z) or FNU+N-1 > 3.27D+04
        IFAIL  = 5 if abs (Z) or FNU+N-1 > 1.07D+09
S17DEF  IFAIL  = 2 if imag (Z) > 81.10
        IFAIL  = 3 if abs (Z) or FNU+N-1 > 3.27D+04
        IFAIL  = 4 if abs (Z) or FNU+N-1 > 1.07D+09
S17DGF  IFAIL  = 3 if abs (Z) > 1.02D+03
        IFAIL  = 4 if abs (Z) > 1.04D+06
S17DHF  IFAIL  = 3 if abs (Z) > 1.02D+03
        IFAIL  = 4 if abs (Z) > 1.04D+06
S17DLF  IFAIL  = 2 if abs (Z) < 5.80D-36
        IFAIL  = 4 if abs (Z) or FNU+N-1 > 3.27D+04
        IFAIL  = 5 if abs (Z) or FNU+N-1 > 1.07D+09
 
S18ADF  IFAIL  = 2 if 0.0 < X <= 5.88D-39
S18AEF  IFAIL  = 1 if abs(X) > 90.28
S18AFF  IFAIL  = 1 if abs(X) > 90.28
S18CDF  IFAIL  = 2 if 0.0 < X <= 5.88D-39
S18DCF  IFAIL  = 2 if abs (Z) < 5.80D-36
        IFAIL  = 4 if abs (Z) or FNU+N-1 > 3.27D+04
        IFAIL  = 5 if abs (Z) or FNU+N-1 > 1.07D+09
S18DEF  IFAIL  = 2 if real (Z) > 81.10
        IFAIL  = 3 if abs (Z) or FNU+N-1 > 3.27D+04
        IFAIL  = 4 if abs (Z) or FNU+N-1 > 1.07D+09
 
S19AAF  IFAIL  = 1 if abs(x) >= 49.50
S19ABF  IFAIL  = 1 if abs(x) >= 49.50
S19ACF  IFAIL  = 1 if X > 121.42
S19ADF  IFAIL  = 1 if X > 121.42
 
S21BCF  IFAIL  = 3 if an argument < 6.512D-26
        IFAIL  = 4 if an argument >= 7.261D+22
S21BDF  IFAIL  = 3 if an argument < 1.806D-13
        IFAIL  = 4 if an argument >= 2.193D+12

(e) X01

The values of the mathematical constants are: 
X01AAF (PI)    = 3.1415926535897932
X01ABF (GAMMA) = 0.5772156649015329

(f) X02

The values of the machine constants are:

The basic parameters of the model 

X02BHF = 2
X02BJF = 56
X02BKF = -127
X02BLF = 127
X02DJF = .TRUE.
Derived parameters of the floating-point arithmetic 
X02AJF = '0000000000002480'X ( 1.387778780781446D-17 )
X02AKF = '0000000000000080'X ( 2.938735877055719D-39 )
X02ALF = 'FFFFFFFFFFFF7FFF'X ( 1.701411834604692D+38 )
X02AMF = '000F000000000100'X ( 5.877471754111441D-39 )
X02ANF = '0001000000000200'X ( 2.350988701644576D-38 )
Parameters of other aspects of the computing environment 
X02AHF = '0000000000007F80'X ( 8.507059173023461D+37 )
X02BBF = 2147483647
X02BEF = 16
X02DAF = .FALSE.

(g) X04

The default output units for error and advisory messages for those routines which can produce explicit output are both Fortran Unit 6.

5. Documentation

Each supported NAG Fortran Library site is ordinarily provided with a printed copy of the NAG Fortran Library Introductory Guide. Additional copies are available for purchase; please refer to the NAG websites or contact your local NAG Response Centre for current prices (see Section 6).

A full on-line version of the NAG Fortran Library Manual is available in the form of Portable Document Format (PDF) files. Please contact NAG if you are interested in this.

6. Support from NAG

(a) Contact with NAG

Queries concerning this document or the implementation generally should be directed initially to your local Advisory Service. If you have difficulty in making contact locally, you can contact NAG directly at one of the addresses given in the Appendix. Users subscribing to the support service are encouraged to contact one of the NAG Response Centres (see below).

(b) NAG Response Centres

The NAG Response Centres are available for general enquiries from all users and also for technical queries from sites with an annually licensed product or support service.

The Response Centres are open during office hours, but contact is possible by fax, email and phone (answering machine) at all times.

When contacting a Response Centre it helps us deal with your enquiry quickly if you can quote your NAG site reference and NAG product code (in this case FLDVV20DA).

(c) NAG Websites

The NAG websites provide information about implementation availability, descriptions of products, downloadable software, product documentation and technical reports. The NAG websites can be accessed at

http://www.nag.co.uk/, http://www.nag.com/ (in North America) or http://www.nag-j.co.jp/ (in Japan)

(d) NAG Electronic Newsletter

If you would like to be kept up to date with news from NAG then please register to receive our free electronic newsletter, which will alert you to special offers, announcements about new products or product/service enhancements, customer stories and NAG's event diary. You can register via one of our websites, or by contacting us at nagnews@nag.co.uk.

7. User Feedback

Many factors influence the way NAG's products and services evolve and your ideas are invaluable in helping us to ensure that we meet your needs. If you would like to contribute to this process we would be delighted to receive your comments. Please contact your local NAG Response Centre (shown below).

Appendix - Contact Addresses

NAG Ltd
Wilkinson House
Jordan Hill Road
OXFORD  OX2 8DR                         NAG Ltd Response Centre
United Kingdom                          email: support@nag.co.uk
 
Tel: +44 (0)1865 511245                 Tel: +44 (0)1865 311744
Fax: +44 (0)1865 310139                 Fax: +44 (0)1865 310139
 
NAG Inc
1431 Opus Place, Suite 220
Downers Grove
IL 60515-1362                           NAG Inc Response Center
USA                                     email: infodesk@nag.com
 
Tel: +1 630 971 2337                    Tel: +1 630 971 2345
Fax: +1 630 971 2706                    Fax: +1 630 971 2706
 
Nihon NAG KK
Hatchobori Frontier Building 2F
4-9-9
Hatchobori
Chuo-ku
Tokyo
104-0032
Japan
email: help@nag-j.co.jp

Tel: +81 (0)3 5542 6311
Fax: +81 (0)3 5542 6312