# formfactor
## English
### Etymology

From form +‎ factor.

### Noun

formfactor (plural formfactors)
* (physics) Any of various calculations representing the shape or distribution of a physical property within a microsystem such as an elementary particle or atomic nucleus.
** 1992, Soviet Physics, Uspekhi - Volume 35, page 11:This electromagnetic structure caused by the cloud of virtual states in the transition region is characterized by a specific formfactor, which is called the transition formfactor.
** 1994, Ricardo Americo Broglia, International School of Heavy Ion Physics, page 391:Dilepton spectroscopy could also give interesting information on the electromagnetic formfactor for baryons where the situation is more complicated since for these the time-like sector is not accessible below an invariant mass of 2mp;
** 2006, G. Höhler, Springer Tracts in Modern Physics, page 131:Using the known values of the nucleon formfactors the pion formfactor can in principle be determined as the only free parameter in a fit to the cross section of electro-π$^+$-production.
** 2007, Maurizio Gasperini, Jnan Maharana, String Theory and Fundamental Interactions, page 747:All diagrams in a given-order formfactor are similar. They all are integrals over the momentum circulating in the loop, and the integrands are identical.
** 2013, J.A. Tjon, “The Three and Four Nucleon Systems (Theory)”, in F. S. Levin, editor, The Few Body Problem, page 49c:The general trend one has found in varying the off-shell behaviour of the two-nucleon interaction while keeping the on-shell properties the same is that though one can in principle increase the binding energy, the dip in the formfactor moves at the same time to larger momentum transfer and as a result the discrepancy in the secondary maximum increases.
** 2015, A.A.Ovchinnikov, “Threshold singularities in the correlators of the one-dimensional models”, in arXiv‎:We calculate the threshold singularities in one-dimensional models using the universal low-energy formfactors obtained in the framework of the non-linear Luttinger liquid model.
* The value of 4π * area / perimeter$^2$, used to measure how well an irregular shape approximates an idealized regular shape, and used to estimate surface area of irregular shapes.
** 1989, Encyclopedia of Materials Science and Engineering, page 503:the surface area of the ellipsoid fitted to the measured length and breadth is divided by the formfactor to estimate the surface area of the irregular object
** 2012, Hans Georg Bock, Willi Jäger, Michael J. Winckler, Scientific Computing and Cultural Heritage, page 104:The formfactor was chosen because it is sensitive to both the elongation of a region and the jaggedness of its border.
** 2017, F. Brent Neal, John C. Russ, Measuring Shape, page 118118:Formfactor is widely used because it is easy to calculate, based on measurements of area and perimeter that must often be carried out anyway.
** 2017, Vladimir L. Gavrikov, Stem Surface Area in Modeling of Forest Stands, page 21:In another publication, Inoue [9] explored the question of whether form-factors for stem volume can help in determining stem surface area.
* (computer graphics) The ratio of energy radiating out from one patch to the energy absorbed by another patch, used in the calculation of radiosity.
** 2012, Gerald Garcia, Ivan Herman, Advances in Computer Graphics, page 95:The formfactor between patches defines the fraction of energy (light) leaving a patch which arrives at the other. The formfactor has proven to be the most computationally expensive part of the radiosity computation for complex environments. The formfactor is purely a function of the geometric relationship between patches, and thus does not depend on viewer position or reflectivity attributes (color) of the surfaces.
** 2012, Björn Engquist, Lennart Johnsson, Michael Hammill, Simulation and Visualization on the Grid, page 101:Formfactor calculation is a very important but time-consuming step when determining a radiosity solution.
** 2013, Kadi Bouatouch, Christian Bouville, Photorealism in Computer Graphics, page 116:For all patches so called formfactors are calculated, that are needed to determine these intensities.
** 2017, John C. Russ, J. Christian Russ, Introduction to Image Processing and Analysis, page 287:In the image, they have been distinguished by assigning a grayscale brightness to each feature that is proportional to a shape descriptor, the formfactor.
* An industry standard that represents the size and shape of a circuit board.
** 1989, Electronic Engineering - Volume 61, page S-59:In the case of embedded RTP systems the most difficult constraint lies in the area of system formfactor limitations .
** 1997, Boot - Volume 2, page 65:Variants include the Baby-AT formfactor.
** 2002 November, “Meet the Formfactors”, in Maximum PC, page 48:Most current consumer motherboards are based on the ATX formfactor, which in turn evolved from the Baby AT formfactor.
** 2010, Silvano Gai, Tommi Salli, Roger Andersson, Cisco Unified Computing System (UCS) (Data Center):The first CNAs to appear on the market were PCIe standard form-factor adapters for industry standard servers, but the same consolidation benefits extend to blade servers using custom form-factor mezzanine cards provided by the server manufacturer.