  The evolution of the total energy surface and the nuclear shape in the
isotopic chain $^{172-194}$Pt are studied in the framework of the interacting
boson model, including configuration mixing. The results are compared with a
self-consistent Hartree-Fock-Bogoliubov calculation using the Gogny-D1S
interaction and a good agreement between both approaches shows up. The
evolution of the deformation parameters points towards the presence of two
different coexisting configurations in the region 176 $\leq$ A $\leq$ 186.
