function factory( options ) {
	var opts;
	var rand;
	var prng;

	opts = {
		'name': defaults.name,
		'copy': defaults.copy
	};
	if ( arguments.length ) {
		if ( !isObject( options ) ) {
			throw new TypeError( format( 'invalid argument. Must provide an object. Value: `%s`.', options ) );
		}
		if ( hasOwnProp( options, 'name' ) ) {
			opts.name = options.name;
		}
		if ( hasOwnProp( options, 'prng' ) ) {
			opts.prng = options.prng;
			if ( opts.prng === void 0 ) {
				throw new TypeError( format( 'invalid option. `%s` option cannot be undefined. Option: `%s`.', 'prng', opts.prng ) );
			}
		} else if ( hasOwnProp( options, 'state' ) ) {
			opts.state = options.state;
			if ( opts.state === void 0 ) {
				throw new TypeError( format( 'invalid option. `%s` option cannot be undefined. Option: `%s`.', 'state', opts.state ) );
			}
		} else if ( hasOwnProp( options, 'seed' ) ) {
			opts.seed = options.seed;
			if ( opts.seed === void 0 ) {
				throw new TypeError( format( 'invalid option. `%s` option cannot be undefined. Option: `%s`.', 'seed', opts.seed ) );
			}
		}
		if ( hasOwnProp( options, 'copy' ) ) {
			opts.copy = options.copy;
			if ( !isBoolean( opts.copy ) ) {
				throw new TypeError( format( 'invalid option. `%s` option must be a boolean. Option: `%s`.', 'copy', opts.copy ) );
			}
		}
	}
	prng = PRNGS[ opts.name ];
	if ( prng === void 0 ) {
		throw new Error( format( 'invalid option. Unrecognized/unsupported PRNG. Option: `%s`.', opts.name ) );
	}
	if ( opts.prng === void 0 ) {
		if ( opts.state === void 0 ) {
			if ( opts.seed === void 0 ) {
				rand = prng.factory();
			} else {
				rand = prng.factory({
					'seed': opts.seed
				});
			}
		} else {
			rand = prng.factory({
				'state': opts.state,
				'copy': opts.copy
			});
		}
	} else {
		rand = prng.factory({
			'prng': opts.prng
		});
	}
	setReadOnly( normal, 'NAME', 'randn' );

	// If we are provided an "external" PRNG, we don't support getting or setting PRNG state, as we'd need to check for compatible state value types, etc, entailing considerable complexity.
	if ( opts.prng ) {
		setReadOnly( normal, 'seed', null );
		setReadOnly( normal, 'seedLength', null );
		setReadWriteAccessor( normal, 'state', constantFunction( null ), noop );
		setReadOnly( normal, 'stateLength', null );
		setReadOnly( normal, 'byteLength', null );
		setReadOnly( normal, 'toJSON', constantFunction( null ) );
	} else {
		setReadOnlyAccessor( normal, 'seed', getSeed );
		setReadOnlyAccessor( normal, 'seedLength', getSeedLength );
		setReadWriteAccessor( normal, 'state', getState, setState );
		setReadOnlyAccessor( normal, 'stateLength', getStateLength );
		setReadOnlyAccessor( normal, 'byteLength', getStateSize );
		setReadOnly( normal, 'toJSON', toJSON );
	}
	setReadOnly( normal, 'PRNG', rand.PRNG );
	return normal;

	/**
	* Returns the PRNG seed.
	*
	* @private
	* @returns {*} seed
	*/
	function getSeed() {
		return rand.seed;
	}

	/**
	* Returns the PRNG seed length.
	*
	* @private
	* @returns {PositiveInteger} seed length
	*/
	function getSeedLength() {
		return rand.seedLength;
	}

	/**
	* Returns the PRNG state length.
	*
	* @private
	* @returns {PositiveInteger} state length
	*/
	function getStateLength() {
		return rand.stateLength;
	}

	/**
	* Returns the PRNG state size (in bytes).
	*
	* @private
	* @returns {PositiveInteger} state size (in bytes)
	*/
	function getStateSize() {
		return rand.byteLength;
	}

	/**
	* Returns the current pseudorandom number generator state.
	*
	* @private
	* @returns {*} current state
	*/
	function getState() {
		return rand.state;
	}

	/**
	* Sets the pseudorandom number generator state.
	*
	* @private
	* @param {*} s - generator state
	* @throws {Error} must provide a valid state
	*/
	function setState( s ) {
		rand.state = s;
	}

	/**
	* Serializes the pseudorandom number generator as a JSON object.
	*
	* ## Notes
	*
	* -   `JSON.stringify()` implicitly calls this method when stringifying a PRNG.
	*
	* @private
	* @returns {Object} JSON representation
	*/
	function toJSON() {
		var out = {};
		out.type = 'PRNG';
		out.name = normal.NAME + '-' + rand.NAME;
		out.state = typedarray2json( rand.state );
		out.params = [];
		return out;
	}

	/**
	* Returns a pseudorandom number drawn from a standard normal distribution.
	*
	* @private
	* @returns {number} pseudorandom number
	*
	* @example
	* var v = normal();
	* // returns <number>
	*/
	function normal() {
		return rand();
	}
}
Returns a pseudorandom number generator for numbers from a standard normal distribution.

@param {Options} [options] - function options
@param {string} [options.name='improved-ziggurat'] - name of pseudorandom number generator
@param {PRNG} [options.prng] - pseudorandom number generator which generates uniformly distributed pseudorandom numbers
@param {*} [options.seed] - pseudorandom number generator seed
@param {*} [options.state] - pseudorandom number generator state
@param {boolean} [options.copy=true] - boolean indicating whether to copy a provided pseudorandom number generator state
@throws {TypeError} must provide an object
@throws {TypeError} must provide valid options
@throws {Error} must provide the name of a supported pseudorandom number generator
@returns {PRNG} pseudorandom number generator

@example
var randn = factory();

var v = randn();
// returns <number>

@example
var randn = factory({
    'name': 'box-muller'
});
var v = randn();
// returns <number>

@example
var randn = factory({
    'seed': 12345
});
var v = randn();
// returns <number>

@example
var randn = factory({
    'name': 'box-muller',
    'seed': 12345
});
var v = randn();
// returns <number>