/** * Calculates the sample standard deviation for a set of data. * @since 7.4.0 */Ext.define('Ext.data.summary.StdDev', { extend: 'Ext.data.summary.Variance', alias: 'data.summary.stddev', /** * Name of the summary function that appears in the {@link Ext.grid.plugin.Summaries} plugin */ text: 'StdDev', calculate: function(records, property, root, begin, end) { var v = this.callParent([records, property, root, begin, end]); if (v != null) { v = Math.sqrt(v); } return v; }});