Accord.Math.Optimization.NonlinearObjectiveFunction.CheckGradient C# (CSharp) Method

        internal static void CheckGradient(Func<double[], double[]> value, double[] probe)
        {
            double[] original = (double[])probe.Clone();
            double[] result = value(probe);

            if (result == probe)
                throw new InvalidOperationException(
                    "The gradient function should not return the parameter vector.");

            if (probe.Length != result.Length)
                throw new InvalidOperationException(
                    "The gradient vector should have the same length as the number of parameters.");

            for (int i = 0; i < probe.Length; i++)
                if (!probe[i].IsEqual(original[i], 0))
                    throw new InvalidOperationException("The gradient function shouldn't modify the parameter vector.");
        }

        /// <summary>
        ///   Finds the minimum value of a function. The solution vector
        ///   will be made available at the <see cref="IOptimizationMethod.Solution"/> property.
        /// </summary>
        ///
        /// <returns>Returns <c>true</c> if the method converged to a <see cref="IOptimizationMethod.Solution"/>.
        ///   In this case, the found value will also be available at the <see cref="IOptimizationMethod.Value"/>
        ///   property.</returns>
        ///
        public override bool Minimize()
        {
            if (Gradient == null)
            {
                throw new InvalidOperationException("gradient");
            }

            NonlinearObjectiveFunction.CheckGradient(Gradient, Solution);

            return(base.Minimize());
        }