function factory( p ) {
	if ( isnan( p ) || p < 0.0 || p > 1.0 ) {
		return constantFunction( NaN );
	}
	return logcdf;

	/**
	* Evaluates the logarithm of the cumulative distribution function (CDF) for a geometric distribution.
	*
	* @private
	* @param {number} x - input value
	* @returns {number} evaluated logCDF
	*
	* @example
	* var y = logcdf( 2.0 );
	* // returns <number>
	*/
	function logcdf( x ) {
		if ( isnan( x ) ) {
			return NaN;
		}
		if ( x < 0.0 ) {
			return NINF;
		}
		if ( x === PINF ) {
			return 0.0;
		}
		x = floor( x );
		return log1p( -pow( 1.0 - p, x + 1.0 ) );
	}
}
Returns a function for evaluating the logarithm of the cumulative distribution function (CDF) for a geometric distribution with success probability `p`.

@param {Probability} p - success probability
@returns {Function} logCDF

@example
var logcdf = factory( 0.5 );
var y = logcdf( 3.0 );
// returns ~-0.065

y = logcdf( 1.0 );
// returns ~-0.288