function logcdf( x ) {
		if ( isnan( x ) ) {
			return NaN;
		}
		if ( x < beta ) {
			return NINF;
		}
		return log1p( -pow( beta / x, alpha ) );
	}
Evaluates the natural logarithm of the cumulative distribution function (CDF) for a Pareto (Type I) distribution.

@private
@param {number} x - input value
@returns {number} evaluated logCDF