Critical phenomena in gravitational collapse were discovered by Choptuik in 1993 in the spherically symmetric collapse of massless scalar field. Since then the phenomenon has been observed in a variety of matter sources. At the threshold of gravitational collapse the matter is just about to form a black hole and an infinitesimally small perturbation can either cause the matter to disperse to infinity or to form a black hole. The dynamics close to the threshold exhibits interesting behaviour such as power law scaling of length scales, self similarity of the solutions and universaity. A typical setup is to take an initial matter distribution parametrized by a single parameter . Then one performs a bisection search to determine the critical value . The critical exponent can be determined from the scaling relation of the black hole mass



Data obtained from subcritical runs for . The line represents the best linear fit to the data. The value of the scaling exponent obtained from the linear fit is 