code: public void setConvergence( int maxIterations , double ftol , double gtol ) {
          this.maxIterations = maxIterations;
          this.ftol = ftol;
          this.gtol = gtol;
      }
docs: Specifies convergence criteria
  
  @param maxIterations Maximum number of iterations
  @param ftol convergence based on change in function value. try 1e-12
  @param gtol convergence based on residual magnitude. Try 1e-12