10.18453/rosdok_id00005822 Mayer, Günter Günter Mayer http://d-nb.info/gnd/13177509X Alefeld, Götz Götz Alefeld http://d-nb.info/gnd/174094442 University of Rostock, Institute of Mathematics 2012 510 Mathematics 2012 en https://purl.uni-rostock.de/rosdok/id00005822 urn:nbn:de:gbv:28-rosdok_id00005822-8 We give a survey on the symmetric solution set of linear systems of equations with perturbed input data starting with a description of its form and presenting several algorithms whose resulting interval vector encloses it. In particular, we derive the describing inequalities in a new way and represent them in a modified form as compared with a recent result by Hlad´ık. This form enables us to improve a known upper bound for their number essentially. We thus end up with an Oettli–Prager like theorem for the symmetric solution set which we can prove by elementary means and completely different from Hladík’s paper.