VPLX is a FORTRAN 77 program developed in the 1990’s for the calculation of variances for complex sample designs through replication. It is in the public domain and is provided here “as is” for historical purposes.

The software is available in the form of Fortran source code. A Fortran compiler (such as f77, f90, or gfortran) will be required to install VPLX.

VPLX evolved within an original syntactic design. To improve the usability of VPLX, a three-phase plan to improve the syntax began in 1997. Version 1998.09 reflects the results of the first phase of revision. It received considerable internal testing at the Census Bureau, and is the release presented here. While a beta version from the second phase of revision was produced and tested internally, it was never released, and development of VPLX ceased.

Requirements

Windows 95/98/NT, Version 1998.09

Version 1998.09 requires at least 16 Meg of RAM and a 486 with a math coprocessor (486 DX ...) or preferably a Pentium or equivalent, running Windows 95, 98 or NT (or newer). Because it is a true 32-bit application, the version will not run under Windows 3.1.

A suitable Fortran compiler is needed to compile the source code. Compilation was tested using Microsoft PowerStation 4.0 and the GNU Fortran compiler (gfortran) and the resulting executable was verified to work on newer versions of Windows, including Windows 10, as a command-line application. VPLX should be installed according to the directions in intra2.pdf. The documentation uses Adobe's Acrobat format, which was described in the section on VPLX documentation.

vplx.f - Source Code [<1.0 MB]

vplerror.txt - Error Messages [<1.0 MB]

intra2.pdf - Installation Instructions [<1.0 MB]

vplx-gfortran-compile-notes.txt - Compile Notes [<1.0 MB]

UNIX Version

The source code to the UNIX version is identical to the Win 95/97/NT version. The Fortran source may be compiled with the GNU Fortran compiler with the “legacy” option, i.e. “gfortran –std=legacy”. The ‘-O3’ option is also recommended to improve execution speed. Compilation notes, including updating the location of the “vplerror.txt” within the source code, are linked below.

vplx.f - Source Code [1.7 MB]

vplerror.txt - Error Messages [<1.0 MB]

vplx-gfortran-compile-notes.txt - Compile Notes [<1.0 MB]

UNIX Notes

There is not general documentation on Unix installation. A few suggestions are included here, however.

vplerror.txt is a file giving interpretations of VPLX error codes, and if vplx knows its location, it will find and display the interpretation of the corresponding error code. Setting the location in the source code is included in the compile notes above.

You may have to use the UNIX command:

chmod u+x,o+x,g+x vplx

to allow the system to recognize the file as an executable. Your system administrator could work with you to choose a directory on the default search path, or to modify initialization files to include the vplx directory on the search path. If this is done, then you may run vplx with:

vplx < commandfile > listfile