datporod
Manual
The following sections briefly describe the method implemented in DATPOROD, how to run DATPOROD from the command-line on any of the supported platforms and the required input files.
Introduction
The excluded volume of a particle can be computed from a scattering curve using the Porod equation. Application of this formula directly to the experimental data can be confronted with difficulties related to high noise level at higher angles; therefore the smooth regularized curve produced by GNOM or DATGNOM is preferred. An appropriate constant \(K^4\) is subtracted from each data point to force the \(s^{-4} decay of the intensity.\)
Running datporod
Usage:
$ datporod [OPTIONS] <SASDATA(S)>
OPTIONS known by DATPOROD are described in next section, the required argument(s) SASDATA(S) in the section on input files.
Command-Line Arguments and Options
DATPOROD requires the following command line arguments:
| Argument | Description |
|---|---|
| SASDATA | One or more experimental SAS data (.dat) or regularised SAS data (.out) files. |
Absolute as well as relative paths to data files are accepted. Instead of a file name, one of the arguments may be given as ‘-‘ to read data from stdin.
DATPOROD recognizes following command-line options:
| Short option | Long option | Description |
|---|---|---|
| --rg <VALUE> | Experimental Radius of Gyration in the units of the data. This option is mandatory for experimental SAS data (.dat). | |
| --i0 <VALUE> | Experimental forward scattering in the units of the data. This option is mandatory for experimental SAS data (.dat). | |
| -v | --version | Print version information and exit. |
| -h | --help | Print a summary of arguments, options, and exit. |
Runtime Output
DATPOROD prints the maximum data angle used (\(s_{max}\)), the volume estimate (Da) and the file name to stdout.
datporod input files
DATPOROD expects background-subtracted experimental SAS data (.dat) or regularised SAS data (.out) files.
If SASDATA is a regularised SAS data (.out) file, reciprocal space \(R_g\) and \(I(0)\) stated in the file are used, but may be overridden by the corresponding command-line options.
Multiple inputs may be provided at once, but note that any --rg and --i0 values specified are applied to all inputs the same.