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Dislocation glide in a matrix containing incoherent spherical particles is simulated on a computer. The critical resolved shear stress (CRSS) is derived. The simulations are based on the local stress equilibrium along the dislocation line. The stress terms taken into account are the external applied stress, a viscous drag stress, the obstacle stress and the dislocation self-stress. The latter stress term is similar to the approaches of Brown [Phil. Mag. 10 (1964) 441] and Bacon [Phys. Stat. Sol. 23 (1967) 527]; it replaces the line tension model and fully allows for the elastic interaction of a dislocation with itself and with other dislocations. The particles have a radii distribution and a three-dimensional spatial arrangement, both of which are close to those of an actual crystal. The CRSS is calculated as a function of the mean particle radius and of the particle volume fraction. This function is compared with a recent theoretical one. If a minor correction to this latter function is permitted, it represents the present simulation results well.