function pickBandwidth( arr, j ) {
	var minElement;
	var sigmaHat;
	var powTerm;
	var iqrVal;
	var out;

	iqrVal = iqr( arr, j ) / 1.34;
	sigmaHat = stdev( arr, j );
	minElement = min( iqrVal, sigmaHat );
	powTerm = pow( arr.shape[ 0 ], -1/5 );
	out = 1.06 * powTerm * minElement;
	if ( out === 0 ) {
		out = EPSILON;
	}
	return out;
}
Computes the rule-of-thumb bandwidth for the values in a column of `x`.

@private
@param {ndarrayLike} arr - input ndarray
@param {number} j - index of the column from which to obtain the values
@returns {NumericArray} array with bandwidth values

@example
var ndarrayLike = require( './ndarray_like.js' );

var x = [ 0.6333, 0.8643, 1.0952, 1.3262, 1.5571, 1.7881, 2.019, 2.25, 2.481, 2.7119 ];
var y = [ -0.0468, 0.8012, 1.6492, 2.4973, 3.3454, 4.1934, 5.0415, 5.8896, 6.7376, 7.5857 ];
var arr = ndarrayLike( x, y );
var out = pickBandwidth( arr, 1 );
// returns ~1.717