code: public void setErrorTolerance(double errorTolerance)
      {
          if(errorTolerance < 0 || errorTolerance > 1 || Double.isNaN(errorTolerance))
              throw new IllegalArgumentException("Error tolerance must be in [0, 1], not " + errorTolerance);
          this.errorTolerance = errorTolerance;
      }
docs: Sets the error tolerance used for certain
  {@link #setBudgetStrategy(jsat.distributions.kernels.KernelPoint.BudgetStrategy) budget strategies}
  @param errorTolerance the error tolerance in [0, 1]