@unpublished{ Hosseini.Uschmajew:2016*1, author = {Seyedehsomayeh Hosseini and Andr{\'e} Uschmajew}, title = {A gradient sampling method on algebraic varieties and application to nonsmooth low-rank optimization}, year = {2016}, month = {oct}, annote = {preprint}, pdf = {http://neitzel.ins.uni-bonn.de/research/pub/hosseini/ProGS.pdf} , note = {INS Preprint No. 1624. Extended and revised version, March 2017}, inspreprintnum= {1624} }