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This manual describes a set of routines which provide data file Input/Output for use with the EPIC system for management, display and analysis of oceanographic or meteorological data. For more information about EPIC, please see the EPIC manual. The EPIC system library is intended for reading and writing geophysical data, and assumes this data is represented by three spatial axes and one time axis.
The EPIC System library supports multiple data file formats. At present, supported formats include the Unidata netCDF format and the Classic EPIC format. Read only support is also provided for generic ASCII file formats and ASCII file formats used internally at PMEL for processing PROTEUS mooring data. Classic EPIC data files are binary sequential files designed for observational data with three of the four space-time axes represented by a single point. NetCDF data files are multi-dimensional, and are transportable between many different types of hardware platforms. Additional data file formats may be supported in the future.
The EPIC system library consists of a "format independent layer", which is a set of generic input/output routines which are called by application programs to open data files, read or write "attributes", axes and data, and then close the files. These routines do not directly manipulate the data files on the disk. Rather, there is a lower level "format dependent layer" of routines for each of the supported data formats. These format dependent routines perform the actual data file manipulations for each of the supported formats. In this way, application programs are freed of dependence on the physical structure of the data files on the disk, additional formats can be supported by the addition of a single set of format dependent routines for the new data file format, and application programs will transparently read and write data files in any of the supported formats without modification.
EPIC system library routines are callable from Fortran and from C, and are supported for Unix machines, VAX/VMS, and Windows NT/Windows95. PMEL provides very simple example application programs, in Fortran and C, which can easily be used as templates for more complex programs. The EPS library and the example programs are available via anonymous ftp: ftp://ftp.epic.noaa.gov/eps/.
HOST: ftp.epci.noaa.gov
DIRECTORY: eps/
eps/examples/
Refer to readme files for more information.
The EPIC System Library User's Guide describes the EPS library routines and their usages. It consists of 9 chapters, including this Introduction chapter.
Chapter 2, EPS File Components gives users an overview of the EPS file components: variables, axes and attributes, and what information these components consist of.
Chapter 3, Examples of the EPS Library Usage provides examples of writing programs which use EPS library routines.
Chapter 4, EPS File Manipulation Routines describes the interfaces of the EPS routines that deal with an EPS file as a whole.
Chapter 5, EPS Time Manipulation Routinesdescribes the interfaces of the EPS time manipulation routines.
Chapter 6, Variable Routinesdescribes the interfaces of EPS variable routines.
Chapter 7, Axis Routines discusses the interfaces of EPS axis routines.
Chapter 8, Attribute Routinesdescribes the interfaces of EPS attribute routines.
In Chapter 4 through Chapter 8, the call syntax of both C and Fortran interfaces are given for each routine including an argument list which identifies data type and dimension of the argument, followed by an argument description. Each argument is identified as either input (boldface I) or output (boldface O). In all cases the C and FORTRAN calls are nearly identical; remarks about C functions apply also to the FORTRAN functions, and vice versa. This is especially important to note when there are remarks about the order in which routines are called. The EPS C interface routines all begin with the letters "ep_" and the FORTRAN interface routines all begin with the letters "ep", except for some time manipulation routines.
Chapter 9, Revision Notes describes the changes have been made since version 1.0 of the EPS library.
Appendix A, Summary of C Interface and Appendix B Summary of FORTRAN Interface summarize the C and FORTRAN interfaces of EPS routines respectively. Appendix C, Epic.key File discusses the epic.key file. Appendix D, EPS Implementation of Unidata NetCDF File Format discusses EPS library implementation of netCDF file format including some limitations of use EPS routines to process netCDF files. Appendix E,EPS Implementation of ASCII Data File Format discusses EPS library implementation of ASCII Data file format.
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