DATGNOM (formerly known as AUTOGNOM) is a tool for automated estimation of the maximum intramolecular distance D_{max}, computation of the distance distribution function p(r) and of the smooth regularized scattering curve (the Fourier transform of p(r)). DATGNOM automatically obtains the p(r) function from an indirect Fourier transform of the scattering profile repeatedly using a regularization procedure implemented in the program GNOM.

The optimum D_{max} is determined from automated comparison of the p(r) functions calculated at different D_{max} values ranging from 2R_{g} to 4R_{g} (with a step of 0.1R_{g}), where R_{g} is the expected radius of gyration. The calculated p(r) functions and corresponding fits to the experimental curves are compared using the perceptual criteria of GNOM, where the smoothness of p(r), absence of systematic deviations in the fit, stability of the solution etc. are merged into a total quality estimate. The behaviour of p(r) near D_{max} is taken into account to ensure that the p(r) function goes smoothly to zero.

Here Dmax is the maximum intramolecular distance, Total is the total quality estimate, Guinier is the same value as the --Rg option, Gnom is the radius of gyration computed from the p(r). The output file will be named "bsa_003.out" because the --output option was not specified.