An inversion is considered completed when: (1) the standard deviation on the cost or the parameters reached the required criteria. This criteria is the parameter STDDEV in the file param.input. It has a typical value of 0.05. It is computed on the NLST last forward computations performed, where NLST is defined in param.input and is has a default value of 50; (2) The maximum number of iterations has been reached. This number is the parameter NIT given in param.input. The default value is 300.