NAG C Library, Mark 8

CLDLL084ZL, License Managed

Windows XP/Vista DLL, Microsoft C/C++

Users' Note


1. Introduction

This document is essential reading for every user of the NAG C Library implementation specified in the title. It provides implementation-specific detail that augments the information provided in the NAG C Library Manual. Wherever that manual refers 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 5):

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

2. Availability of Routines

All routines listed in the chapter contents documents of the NAG C Library Manual, Mark 8 are available in this implementation. Please consult Mark 8 News (see Section 5) for a list of new routines and for a list of routines scheduled for withdrawal at future Marks. Your suggestions for new algorithms for future releases of the Library are welcomed (see Section 7).

3. General Information

3.1. Accessing the Library

In this section we assume that the Library has been installed in the default folder:
  C:\Program Files\NAG\CL08\cldll084zl
If this folder does not exist, please consult the system manager (or the person who did the installation). In some of the information given here, this folder is referred to as install dir.

We also assume that the default shortcut for the Library command prompt is placed in the Start Menu under:

  Start|All Programs|NAG|CL08
If this shortcut does not exist, please consult the system manager (or the person who did the installation). (Other shortcuts created as part of the Library installation procedure are also assumed to be in this location.)

To ensure that the NAG DLLs are accessible at runtime, the install dir\bin folder must be on the path. If the MKL version of the DLL is to be used, the install dir\MKL_ia32_8.0\bin folder must also be on the path, but should appear later in the path than the install dir\bin folder, since the NAG versions of a few BLAS/LAPACK routines are included in CLDLL084Z_mkl.dll to avoid problems with the vendor versions. (See Section 4 for details.)

To check the accessibility of the NAG DLLs, run the program NAG_C_DLL_info.exe which is available from the Start Menu shortcut

  NAG C Library DLLs (CLDLL084ZL). Check Accessibility
See Section 3.2 for details of this utility.

The PATH, LIB and INCLUDE environment variables may already have been set globally as part of the installation or this may be done via the Control Panel. (On Windows XP, from Control Panel select System | Advanced | Environment Variables; on Vista from Control Panel select System and Maintenance (if not using Classic View), then System | Advanced System Settings | Environment Variables... .) Either the user or the system variables may be edited, although Administrator privileges will be required to edit the system ones. Edit the PATH environment variable to include

  c:\Program Files\NAG\CL08\cldll084zl\batch;
  c:\Program Files\NAG\CL08\cldll084zl\bin;
  c:\Program Files\NAG\CL08\cldll084zl\MKL_ia32_8.0\bin;
  existing path
add or edit the LIB environment variable to include
  c:\Program Files\NAG\CL08\cldll084zl\lib;
  c:\Program Files\NAG\CL08\cldll084zl\MKL_ia32_8.0\lib;
  any existing library path
add or edit the INCLUDE environment variable to include
  c:\Program Files\NAG\CL08\cldll084zl\include;
  any existing include path
substituting the correct folder where the NAG C DLLs are installed if necessary.

Alternatively, if you wish to access this implementation from a command prompt window, the environment variables may be set locally.

The shortcut:

  NAG C Library DLLs (CLDLL084ZL). Command Prompt
may be used to start a command prompt window with the correct settings for the INCLUDE, LIB and PATH environment variables for the Library and supplied MKL. The environment variable NAG_CLDLL084ZL, which is needed by the nagc_example*.bat batch files (see Section 3.3), is also set.

If the shortcut is not used, you can set the environment variables by running the batch file envvars.bat for this implementation. The default location for this file is:

  C:\Program Files\NAG\CL08\cldll084zl\batch\envvars.bat
If this file is not in the default location, you can locate it by searching for the file envvars.bat containing cldll084zl.

In this DLL implementation, for convenience, the MKL symbols are exported directly from the NAG import library CLDLL084Z_mkl.lib, so it is not necessary to specify the MKL import libraries libguide40.lib and mkl_s_dll.lib as well. However, if the MKL import libraries are specified, it is important that the NAG import library preceeds them, i.e. the order should be

  CLDLL084Z_mkl.lib libguide40.lib mkl_s_dll.lib
because certain parts of the MKL should not be used (see Section 4).

Information on calling the NAG C DLLs from various different environments is described in the separate document Using the NAG C Library Windows DLLs. Further information on calling NAG C or Fortran DLLs is available on the NAG web site at

3.2. Accessibility Check

The diagnostic program NAG_C_DLL_info.exe, which by default is located in C:\Program Files\NAG\CL08\cldll084zl\diagnostics, may be used to check whether the DLLs CLDLL084Z_nag.dll and CLDLL084Z_mkl.dll are accessible from the current environment. If this program is started from Windows Explorer or from the
  Start|All Programs|NAG|CL08|NAG C Library DLLs
      (CLDLL084ZL). Check Accessibility
shortcut on the Start Menu, the DLLs will be found if the global PATH environment variable has been set to include their location. If it is run from a Command Prompt window, then the environment local to that window will prevail. (See Section 3.1 for more information on environment variables.)

For each of the DLLs that it loads successfully, NAG_C_DLL_info.exe will print the location of the DLL, and pop up a message box showing the implementation details as provided by a call to the routine a00aac. It also calls a00acc to check the availability of a valid license key if required by the implementation and reports if this is not found; "Status OK" indicates that a valid key was either found or not required.

3.3. Example Programs

This section assumes that you are calling the NAG DLLs from a command line Microsoft C program. If you are calling the DLLs from a different compiler, you may wish to modify the batch files accordingly. See Using the NAG C Library Windows DLLs for information on calling the DLLs from various different systems.

The example programs are most easily accessed using the batch files nagc_example.bat or nagc_example_mkl.bat, which can be found in the "batch" folder. These batch files will provide you with a copy of an example program (and its data, if any), compile the program and link it with the appropriate libraries (showing you the compile command so that you can recompile your own version of the program). Finally, the executable program will be run.

These batch files require that the environment variables for Microsoft C/C++ and the NAG C Library are set. In particular, the environment variable NAG_CLDLL084ZL needs to be set to the location of the NAG C Library. Please see Section 3.1 for details of how to do this.

The example program concerned is specified by the argument to the command, e.g.

  nagc_example_mkl d01ajc
will copy the example program into the file d01ajce.c in the current folder and process it to produce the example program results (d01ajce.r in this case). (If the example has a corresponding data file, this too will be copied to the current folder.)

Alternatively you could use:

  nagc_example d01ajc

The difference between nagc_example_mkl.bat and nagc_example.bat is that while nagc_example_mkl.bat uses the library CLDLL084Z_mkl.lib and the MKL BLAS/LAPACK libraries, nagc_example.bat uses the self-contained library CLDLL084Z_nag.lib. The executables created will use CLDLL084Z_mkl.dll and CLDLL084Z_nag.dll respectively.

If you have problems when calling a NAG routine using CLDLL084Z_mkl.lib or CLDLL084Z_mkl_bc.lib, we suggest that you use the self-contained libraries CLDLL084Z_nag.lib or CLDLL084Z_nag_bc.lib. (CLDLL084Z_mkl_bc.lib and CLDLL084Z_nag_bc.lib are the import libraries for use with the Borland C++ compiler.)

The example programs are supplied in machine-readable form. They are suitable for immediate usage. 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.

The distributed example results are those obtained with the NAG self-contained library CLDLL084Z_nag.dll (using the NAG BLAS and LAPACK routines). Running the examples with MKL BLAS or LAPACK may give slightly different results.

Please note that with this DLL version of the library, if you are not using Release 8.0 (Version 14.00.50727.42) of the Microsoft Visual C++ compiler, mixing output from your C code with output from NAG C Library functions, e.g. x04 chapter functions, may result in output files where results appear in the wrong order. This is apparent when running the NAG Example Programs, e.g. c06pfce.c, where titles written by the C example code appear after the matrices printed by the NAG C Library. This is caused by having two different C run time libraries linked to the executable, using buffered output which is flushed independently by each run time library. Similarly, code that relies on reading the same input file from C code and also via a NAG C Library function will not work as the current file pointer will not be shared by the two run time libraries. This may be seen in the failure of the NAG C Library Example Program e04nrce.c, which reads data for the C example and options for the NAG C Library function from the same file.

A more detailed description of this problem may be found on the NAG web site at

These problems are not found in the static implementation of the NAG C Library (CLW3208DAL).

4. Routine-specific Information

Any further information which applies to one or more routines in this implementation is listed below, chapter by chapter.
  1. f08

    In this implementation calls to the NAG version of the following Basic Linear Algebra Subprograms (BLAS) and linear algebra routines (LAPACK) are included in the library CLDLL084Z_mkl.dll to avoid problems with the MKL version:

  2. s10 - s21

    Functions in this chapter will give error messages if called with illegal or unsafe arguments. General details are given in the NAG C Library Manual, but parameter limits which are implementation specific are given below:
    s10aac  E(1)      = 1.8500e+1
    s10abc  fail.code = NE_REAL_ARG_GT if X > 7.080e+2
    s10acc  fail.code = NE_REAL_ARG_GT if X > 7.080e+2
    s13aac  X(hi)     = 7.083e+2
    s13acc  X(hi)     = 1.0e+16
    s13adc  X(hi)     = 1.0e+17
    s14aac  fail.code = NE_REAL_ARG_GT if X > 1.70e+2
            fail.code = NE_REAL_ARG_LT if X < -1.70e+2
            fail.code = NE_REAL_ARG_TOO_SMALL if ABS(X) < 2.23e-308
    s14abc  fail.code = NE_REAL_ARG_GT if X > 2.55e+305
    s17acc  fail.code = NE_REAL_ARG_GT if X > 1.0e+16
    s17adc  fail.code = NE_REAL_ARG_GT if X > 1.0e+16
            fail.code = NE_REAL_ARG_TOO_SMALL if X <= 2.23e-308
    s17aec  fail.code = NE_REAL_ARG_GT if ABS(X) > 1.0e+16
    s17afc  fail.code = NE_REAL_ARG_GT if ABS(X) > 1.0e+16
    s17agc  fail.code = NE_REAL_ARG_GT if X > 1.038e+2
            fail.code = NE_REAL_ARG_LT if X < -5.6e+10
    s17ahc  fail.code = NE_REAL_ARG_GT if X > 1.041e+2
            fail.code = NE_REAL_ARG_LT if X < -5.6e+10
    s17ajc  fail.code = NE_REAL_ARG_GT if X > 1.041e+2
            fail.code = NE_REAL_ARG_LT if X < -1.8e+9
    s17akc  fail.code = NE_REAL_ARG_GT if X > 1.041e+2
            fail.code = NE_REAL_ARG_LT if X < -1.8e+9
    s18adc  fail.code = NE_REAL_ARG_TOO_SMALL if 0.0D+00 < X <= 2.23e-308
    s18aec  fail.code = NE_REAL_ARG_GT if ABS(X) > 7.116e+2
    s18afc  fail.code = NE_REAL_ARG_GT if ABS(X) > 7.116e+2
    s18cdc  fail.code = NE_REAL_ARG_TOO_SMALL if 0.0D+00 < X <= 2.23e-308
    s19aac  fail.code = NE_REAL_ARG_GT if ABS(X) >= 4.95000e+1
    s19abc  fail.code = NE_REAL_ARG_GT if ABS(X) >= 4.95000e+1
    s19acc  fail.code = NE_REAL_ARG_GT if X > 9.9726e+2
    s19adc  fail.code = NE_REAL_ARG_GT if X > 9.9726e+2
    s21bcc  fail.code = NE_REAL_ARG_LT if an argument < 1.579e-205
            fail.code = NE_REAL_ARG_GE if an argument >= 3.774e+202
    s21bdc  fail.code = NE_REAL_ARG_LT if an argument < 2.820e-103
            fail.code = NE_REAL_ARG_GT if an argument > 1.404e+102
  3. x01

    The values of the mathematical constants are provided in the header file nagx01.h
    X01AAC (pi)    = 3.14159265358979323846e+00
    X01ABC (gamma) = 0.5772156649015328606e+00
  4. x02

    The values of the machine constants are provided in in the header file nagx02.h

    The basic parameters of the model

    X02BHC = 2
    X02BJC = 53
    X02BKC = -1021
    X02BLC = 1024
    X02DJC = Nag_TRUE

    Derived parameters of the floating-point arithmetic

    X02AJC = 1.11022302462516e-16
    X02AKC = 2.22507385850721e-308
    X02ALC = 1.79769313486231e+308
    X02AMC = 2.22507385850721e-308
    X02ANC = 2.22507385850721e-308

    Parameters of other aspects of the computing environment

    X02AHC = 1.84467440737095e+19
    X02BBC = 2147483647
    X02BEC = 15
    X02DAC = Nag_FALSE
  5. x03

    x03aaw and x03aax are internal functions which are exported from this NAG C Library implementation as they may be useful when calling the DLLs from environments such as Excel (as explained below).

    The function x03aaw changes the floating-point control word such that it sets the working precision to double precision (53-bit mantissa) and sets the rounding mode to nearest. x03aaw takes a single int argument, which is used to store the floating-point control word value on input and return it to the calling program, so this function is also used to retrieve the original (i.e. on entry) value of the control word.

    The function x03aax sets the floating-point control word to the value specified in its single int argument. It is typically used to restore the floating-point control word to its original value after a call to x03aaw, but may, of course, be used to set a different value.

    The Library has been tested using programs compiled with Microsoft C++ which sets the floating point control word to double precision. Other environments may set the floating point control word to extended precision, e.g. Excel and gcc. In almost all cases this is not a problem but in some rare cases, in order to obtain consistent behaviour the user may wish to use x03aaw directly before entering any other Library function in order to restore the mode of operation to double precision.

    A corollary of the behaviour of these two functions is that they may also be used as a "get and set" pair, with x03aaw used to get the value of the floating-point control word on entry, and x03aax used to set a new value (or restore the original value), but note the "side-effect" of calling x03aaw, namely that this will set the control word to double precision.

5. Documentation

A full online version of the NAG C Library Manual is supplied in the form of Portable Document Format (PDF) files, with an HTML index, in the manual folder. The introductory material is also provided as HTML files in the manual folder.

A main index file has been provided (manual\html\mark8.html) which contains a fully linked contents document pointing to all the available PDF (and where available HTML) files. This index file is available from the Start Menu under

  Start|All Programs|NAG|CL08|NAG C Library Manual
by default. Use your HTML browser to navigate from here.

In addition the following are provided:

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 CLDLL084ZL).

(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 the following URLs:, or

(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

(e) Product Registration

To ensure that you receive information on updates and other relevant announcements, please register this product with us. For NAG Library products this may be accomplished by filling in the online registration form at

7. User Feedback

Many factors influence the way that 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 any of the NAG Response Centres (shown below).

Appendix - Contact Addresses

Wilkinson House
Jordan Hill Road
OXFORD  OX2 8DR                         NAG Ltd Response Centre
United Kingdom                          email:

Tel: +44 (0)1865 511245                 Tel: +44 (0)1865 311744
Fax: +44 (0)1865 310139                 Fax: +44 (0)1865 310139

1431 Opus Place, Suite 220
Downers Grove
IL 60515-1362                           NAG Inc Response Center
USA                                     email:

Tel: +1 630 971 2337                    Tel: +1 630 971 2337
Fax: +1 630 971 2706                    Fax: +1 630 971 2706

Nihon NAG KK
Hatchobori Frontier Building 2F

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