Accord.Math.Optimization.QuadraticConstraint.gradient C# (CSharp) Method

        private double[] gradient(double[] x)
        {
            double[] g = new double[x.Length];

            for (int i = 0; i < x.Length; i++)
            {
                // Calculate quadratic terms
                g[i] = 2.0 * x[i] * QuadraticTerms[i, i];
                for (int j = 0; j < x.Length; j++)
                    if (i != j) g[i] += x[j] * (QuadraticTerms[i, j] + QuadraticTerms[j, i]);

                // Calculate for linear terms
                g[i] += LinearTerms[i];
            }

            return g;
        }
    }