function variancePortfolio($weights, $returns) { $TranspWeight = $this->transpose($weights); $ArrayCov = $this->covarianceMatrix($returns); $object1 = new self($weights, $ArrayCov); $Mult = $object1->multiplicationMatrix($weights, $ArrayCov); $object2 = new self($Mult, $TranspWeight); $MatrixCovPort = $object2->multiplicationMatrix($Mult, $TranspWeight); $CovPort = $MatrixCovPort[0]; return $CovPort; }