def _calc_ocsb_crit_val(m):
        """Compute the OCSB critical value"""
        # See:
        # https://github.com/robjhyndman/forecast/blob/
        # 8c6b63b1274b064c84d7514838b26dd0acb98aee/R/unitRoot.R#L409
        log_m = np.log(m)
        return -0.2937411 * \
            np.exp(-0.2850853 * (log_m - 0.7656451) + (-0.05983644) *
                   ((log_m - 0.7656451) ** 2)) - 1.652202
def _calc_ocsb_crit_val ( m ) : log_m = np . log ( m ) return - 0.2937411 * np . exp ( - 0.2850853 * ( log_m - 0.7656451 ) + ( - 0.05983644 ) * ( ( log_m - 0.7656451 ) ** 2 ) ) - 1.652202
Compute the OCSB critical value