code: function (n, d, s) {
  		var uses = typeof s !== 'undefined';
  		var x = [];
  		for (var i = 0; i < n; i++) {
  			var xhere = [];
  			for (var j = 0; j < d; j++) {
  				if (uses) {
  					xhere.push(s);
  				} else {
  					xhere.push(randn(0.0, 1e-4));
  				}
  			}
  			x.push(xhere);
  		}
  		return x;
  	}
docs: utility that returns 2d array filled with random numbers or with value s, if provided