Evaluate: routine to evaluate a compley polynomial

src/Numerics/SpecialFunctions/Evaluate.cs

@@ -50,6 +50,10 @@ namespace MathNet.Numerics
 {
     using System;
 
+#if !NOSYSNUMERICS
+    using Complex = System.Numerics.Complex;
+#endif
+
     /// <summary>
     /// Evaluation functions, useful for function approximation.
     /// </summary>
@@ -74,6 +78,44 @@ namespace MathNet.Numerics
             return sum;
         }
 
+        /// <summary>
+        /// Evaluate a polynomial at point x.
+        /// Coefficients are ordered by power with power k at index k.
+        /// Example: coefficients [3,-1,2] represent y=2x^2-x+3.
+        /// </summary>
+        /// <param name="z">The location where to evaluate the polynomial at.</param>
+        /// <param name="coefficients">The coefficients of the polynomial, coefficient for power k at index k.</param>
+        public static Complex Polynomial(Complex z, params double[] coefficients)
+        {
+            Complex sum = coefficients[coefficients.Length - 1];
+            for (int i = coefficients.Length - 2; i >= 0; --i)
+            {
+                sum *= z;
+                sum += coefficients[i];
+            }
+
+            return sum;
+        }
+
+        /// <summary>
+        /// Evaluate a polynomial at point x.
+        /// Coefficients are ordered by power with power k at index k.
+        /// Example: coefficients [3,-1,2] represent y=2x^2-x+3.
+        /// </summary>
+        /// <param name="z">The location where to evaluate the polynomial at.</param>
+        /// <param name="coefficients">The coefficients of the polynomial, coefficient for power k at index k.</param>
+        public static Complex Polynomial(Complex z, params Complex[] coefficients)
+        {
+            Complex sum = coefficients[coefficients.Length - 1];
+            for (int i = coefficients.Length - 2; i >= 0; --i)
+            {
+                sum *= z;
+                sum += coefficients[i];
+            }
+
+            return sum;
+        }
+
         /// <summary>
         /// Numerically stable series summation
         /// </summary>