def transform_tev(t, rho, x):
 def _check_args(rho, x):
  cond1 = (x > 0)
  cond2 = ((rho > 0) and (rho < 1))
  return (cond1 and cond2)
 if (not np.all(_check_args(rho, x))):
  raise ValueError('invalid args')
 from scipy.stats import t as stats_t
 z = (np.sqrt((1.0 + x)) * (np.power((t / (1.0 - t)), (1.0 / x)) - rho))
 z /= np.sqrt((1 - (rho * rho)))
 transf = (((1 - t) * stats_t._cdf(z, (x + 1))) + (t * stats_t._cdf(z, (x + 1))))
 return transf

def transform_tev ( t , rho , x ) : def _check_args ( rho , x ) : cond1 = ( x > 0 ) cond2 = ( ( rho > 0 ) and ( rho < 1 ) ) return ( cond1 and cond2 ) if ( not np . all ( _check_args ( rho , x ) ) ) : raise ValueError ( 'invalid args' ) from scipy . stats import t as stats_t z = ( np . sqrt ( ( 1.0 + x ) ) * ( np . power ( ( t / ( 1.0 - t ) ) , ( 1.0 / x ) ) - rho ) ) z /= np . sqrt ( ( 1 - ( rho * rho ) ) ) transf = ( ( ( 1 - t ) * stats_t . _cdf ( z , ( x + 1 ) ) ) + ( t * stats_t . _cdf ( z , ( x + 1 ) ) ) ) return transf
t-ev model of demarta and mcneil 2005 restrictions: - rho in - x > 0 .