Add equalent np.convolve (just full mode)

src/NumSharp/Extensions/NdArray.Convolve.cs

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+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Text;
+using NumSharp;
+
+namespace NumSharp.Extensions
+{
+    public static partial class NDArrayExtension
+    {
+        /// <summary>
+        /// Convolution of 2 series  
+        /// </summary>
+        /// <param name="numSharpArray1"></param>
+        /// <param name="numSharpArray2"></param>
+        /// <param name="mode"></param>
+        /// <returns></returns>
+        public static NDArray<double> Convolve(this NDArray<double> numSharpArray1, NDArray<double> numSharpArray2, string mode  = "full")
+        {
+            int nf = numSharpArray1.Length;
+            int ng = numSharpArray2.Length;
+
+            var numSharpReturn = new NDArray<double>();
+
+            if (mode.Equals("full"))
+            {
+                int n  = nf + ng - 1;
+
+                var out_ = new double[n];
+
+                for (int idx = 0; idx < n; ++idx)
+                {
+                    int jmn = (idx >= ng - 1) ? (idx - (ng - 1)) : 0;
+                    int jmx = (idx < nf - 1) ? idx : nf - 1;
+
+                    for (int jdx = jmn; jdx <= jmx; ++jdx )
+                    {
+                        out_[idx] += ( numSharpArray1[jdx] * numSharpArray2[idx - jdx] );
+                    }
+                }
+
+                numSharpReturn.Data = out_;
+            }
+            else 
+            {
+
+            }
+
+            return numSharpReturn;
+        }
+    }
+  }

test/NumSharp.UnitTest/Extensions/NdArray.Convolve.Test.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+using NumSharp.Extensions;
+using System.Linq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace NumSharp.UnitTest.Extensions
+{
+    /// <summary>
+    /// Test concolve with standard example from 
+    /// https://www.numpy.org/devdocs/reference/generated/numpy.convolve.html
+    /// </summary>
+    [TestClass]
+    public class NdArrayConvolveTest
+    {
+        [TestMethod]
+        public void ConvoleFull()
+        {
+            var series1 = new NDArray<double>();
+            series1.Data = new double[]{1, 2, 3};
+
+            var series2 = new NDArray<double>();
+            series2.Data = new double[]{0, 1, 0.5};
+
+            var series3 = series1.Convolve(series2);
+
+            double[] expectedResult = new double[]{0, 1, 2.5, 4, 1.5};
+
+            Assert.IsTrue(Enumerable.SequenceEqual(series3.Data.ToArray(), expectedResult));
+        }
+        [TestMethod]
+        public void ConvoleValid()
+        {
+            // To be done 
+        }
+        [TestMethod]
+        public void ConvoleSame()
+        {
+            // To be done 
+        }
+
+    }
+}