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All of the PSCF programs are designed to be run from a unix command line, and all have a similar command line interface. The names of the parameter and command files required to perform a computation are passed to the the program as arguments of the "-p" and "-c" command line options, respectively. Names of other input and output files are provided as arguments to commands in the command file.
Example
As an example, consider use of the program pscf_1d, which is used to simulate problems in which the fields depend on a single coordinate. To run this program using a parameter file named "param" and command file named "commands" that are both in the current working directory, one would enter
The syntax to invoke the pscf_pc and pscf_pg programs for periodic microstructures is similar, but requires that parameter also pass the spatial dimensionality as a parameter of the -d option. For example, to use pscf_pc to perform a calculation involving a three-dimensional periodic microstructures, one would enter
The command line interface for pscf_pg is identical to the interface for pscf_pc.
During execution, some log information is written to standard output, which outputs to a terminal by default. This log output can be re-directed to a file by using the unix ">" output redirect operator. For example, the command
would direct standard output to a file named "log" in the current working directory. Standard output should normally be redirected to a file when a job is run in background or in a queue.
Echoing the Parameter File
All PSCF programs accept a command line option "-e" that causes the contents of each line of the parameter file to be echoed to standard output while the parameter file is being read. For example, to invoke pscf_pc with echoing of the parameter file to a log file, one could enter
The "echo" option is very useful for locating errors in the parameter file. When an error is detected while reading a parameter file, the echoed output ends immediately before the line at which the error is detected, and is followed by an error message with any avaiable information about the nature of the error.
PSCF parameter files are fixed-format files in which every element is preceded by a label string that gives the name of a parameter or a block of parameters. During processing of the parameter file, the program reads each such label and compares it to a label that it expects to appear next in the file. Error messages that are generated in response to parameter file syntax errors output both the expected label string and the label string that was actually read from file. This error message is usually enough to allow a user to identify and fix such an error.
Another advantage of using the echo option is that it creates an output that indicates the existence of optional elements that are allowed by the parameter file format but that were omitted in a particular parameter file. If an optional parameter or subblock is omitted, the label of the omitted element is echoed to standard output followed by the string "[absent]". The inclusion of omitted optional elements in the echoed output may help users more quickly become familiar with the full format of each parameter file block, including optional elements that are omitted from some examples.
Command Line Options
The table shown below lists all command line options accepted by PSCF programs. The second column, which describes the option parameter, is left empty for options that do not take a parameter. All but one of the options listed below can be used with any of the three PSCF programs. The only exception to this is the -d option, which is a required input to the pscf_pc and pscf_pg programs, but is not a valid option for pscf_1d.
| Option | Parameter | Description |
| -d | dimension | spatial dimensionality 1, 2, or 3 (required for pscf_pc and pscf_pg) |
| -p | filename | Name of the parameter file (required) |
| -c | filename | Name of the command file (required) |
| -i | prefix | string that is prepended to the paths for all input data files (optional) |
| -o | prefix | string that is prepended to the the paths for all output data files (optional) |
| -e | Activates echoing of parameter file to standard output (optional) |
The -p and -c options are required, while the -i, -o and -e options are optional. The -d option only exists for the pscf_pc and pscf_pg programs, and is required for those programs. The -e option does not take a parameter.
The "prefix" parameters of the -i and -o options is often used to specify directories for input and output files. To do so, set either of these arguments to the path to a directory, terminated by the directory separator charactor "/", giving a string such as "in/" or "out/".
These prefix strings are prepended verbatim to names of input and output files that are specified a parameters in the command file, but are not added to the names of the parameter and command files specified in the program command line interface.
Example : The command
would run the pscf_pc using a parameter file named "param" and a command file named "commands", while echoing the parameter file during initialization, writing all output files to subdirectory "out/" of the current working directory, and reading all input files other than the parameter and command files from subdirectory "in/".
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