<?php
    public function getAssetAllocation(Depot $depot)
    {
        $stocks = $depot->getStocks();
        $stockCount = count($stocks);
        $step = 0.01;
        $maxIterations = ($stockCount - $step) / $step;

        for ($i = 0; $i <= $maxIterations; $i++) {
            // 3 possible values: +$step -$step and 0
            for ($t = 0; $t <= 17; $t++) {
                $depots[$t] = clone $depot;

                /**
                 * build variants with depots
                 */
                /** @var Stock $stock */
                foreach ($depots[$t]->getStocks() as $stock) {
                    $stock->setAmount();
                }

                /**
                 * get current yield/volatility
                 */
                $currentYield = $this->getDepotExpectedYield($depot);
                $currentVola = $this->getDepotStandardDeviation($depot);
                
                /**
                 * get the depot with best yield/volatility ratio
                 */
                foreach($depots as $key => $d){
                    $yield = $this->getDepotExpectedYield($d);
                    $vola = $this->getDepotStandardDeviation($d);
                    
                    if($vola <= $currentVola && $yield >= $currentYield){
                        // better match found. change $depot to new one.
                        $depot = $d;
                    }
                }
                
            }
        }
    }