function iterLogspace( start, stop, N, options ) {
	var step;
	var iter;
	var FLG;
	var b;
	var n;
	var d;
	var i;

	if ( !isNumber( start ) || isnan( start ) ) {
		throw new TypeError( format( 'invalid argument. First argument must be a number. Value: `%s`.', start ) );
	}
	if ( !isNumber( stop ) || isnan( stop ) ) {
		throw new TypeError( format( 'invalid argument. Second argument must be a number. Value: `%s`.', stop ) );
	}
	if ( arguments.length === 3 ) {
		if ( isNonNegativeInteger( N ) ) {
			n = N;
			b = DEFAULT_BASE;
		} else if ( isPlainObject( N ) ) {
			n = DEFAULT_LEN;
			if ( hasOwnProp( N, 'base' ) ) {
				if ( !isPositiveNumber( N.base ) ) {
					throw new TypeError( format( 'invalid option. `%s` option must be a positive number. Option: `%s`.', 'base', N.base ) );
				}
				b = N.base;
			} else {
				b = DEFAULT_BASE;
			}
		} else {
			throw new TypeError( format( 'invalid argument. Third argument must be either a nonnegative integer or an object. Value: `%s`.', N ) );
		}
	} else if ( arguments.length >= 4 ) {
		if ( !isNonNegativeInteger( N ) ) {
			throw new TypeError( format( 'invalid argument. Third argument must be a nonnegative integer. Value: `%s`.', N ) );
		}
		n = N;
		if ( !isPlainObject( options ) ) {
			throw new TypeError( format( 'invalid argument. Fourth argument must be an object. Value: `%s`.', options ) );
		}
		if ( hasOwnProp( options, 'base' ) ) {
			if ( !isPositiveNumber( options.base ) ) {
				throw new TypeError( format( 'invalid option. `%s` option must be a positive number. Option: `%s`.', 'base', options.base ) );
			}
			b = options.base;
		} else {
			b = DEFAULT_BASE;
		}
	} else {
		n = DEFAULT_LEN;
		b = DEFAULT_BASE;
	}
	d = n - 1;
	step = (stop-start) / d;
	i = -1;

	// Create an iterator protocol-compliant object:
	iter = {};
	setReadOnly( iter, 'next', next );
	setReadOnly( iter, 'return', end );

	// If an environment supports `Symbol.iterator`, make the iterator iterable:
	if ( iteratorSymbol ) {
		setReadOnly( iter, iteratorSymbol, factory );
	}
	return iter;

	/**
	* Returns an iterator protocol-compliant object containing the next iterated value.
	*
	* @private
	* @returns {Object} iterator protocol-compliant object
	*/
	function next() {
		i += 1;
		if ( FLG || i >= n ) {
			return {
				'done': true
			};
		}
		if ( i === 0 ) {
			return {
				'value': pow( b, start ),
				'done': false
			};
		}
		if ( i === d ) {
			return {
				'value': pow( b, stop ),
				'done': false
			};
		}
		return {
			'value': pow( b, (i*step)+start ),
			'done': false
		};
	}

	/**
	* Finishes an iterator.
	*
	* @private
	* @param {*} [value] - value to return
	* @returns {Object} iterator protocol-compliant object
	*/
	function end( value ) {
		FLG = true;
		if ( arguments.length ) {
			return {
				'value': value,
				'done': true
			};
		}
		return {
			'done': true
		};
	}

	/**
	* Returns a new iterator.
	*
	* @private
	* @returns {Iterator} iterator
	*/
	function factory() {
		return iterLogspace( start, stop, n, {
			'base': b
		});
	}
}
Returns an iterator which returns evenly spaced numbers on a log scale.

@param {number} start - exponent of starting value (inclusive)
@param {number} stop - exponent of stopping value (inclusive)
@param {NonNegativeInteger} [N=100] - number of values
@param {Options} [options] - function options
@param {PositiveNumber} [options.base=10] - base of log space
@throws {TypeError} first argument must be a number
@throws {TypeError} second argument must be a number
@throws {TypeError} `N` argument must be a nonnegative integer
@throws {TypeError} `options` argument must be an object
@throws {TypeError} must provide valid options
@returns {Iterator} iterator

@example
var iter = iterLogspace( 0, 3, 4 );

var v = iter.next().value;
// returns 1

v = iter.next().value;
// returns 10

v = iter.next().value;
// returns 100

// ...