[cs] add MulVec for G2

ffi/cs/mcl/mcl.cs

@@ -88,6 +88,7 @@ namespace mcl {
         [DllImport(dllName)] public static extern void mclBnG2_add(ref G2 z, in G2 x, in G2 y);
         [DllImport(dllName)] public static extern void mclBnG2_sub(ref G2 z, in G2 x, in G2 y);
         [DllImport(dllName)] public static extern void mclBnG2_mul(ref G2 z, in G2 x, in Fr y);
+        [DllImport(dllName)] public static extern void mclBnG2_mulVec(ref G2 z, [In] G2[] x, [In] Fr[] y, long n);
 
         [DllImport(dllName)] public static extern void mclBnGT_clear(ref GT x);
         [DllImport(dllName)] public static extern int mclBnGT_setStr(ref GT x, [In][MarshalAs(UnmanagedType.LPStr)] string buf, long bufSize, int ioMode);
@@ -249,6 +250,14 @@ namespace mcl {
         {
             mclBnG2_normalize(ref y, x);
         }
+        public static void MulVec(ref G2 z, in G2[] x, in Fr[] y)
+        {
+            int n = x.Length;
+            if (n <= 0 || n != y.Length) {
+                throw new ArgumentException("bad length");
+            }
+            mclBnG2_mulVec(ref z, x, y, (long)n);
+        }
         public static void Add(ref GT z, in GT x, in GT y)
         {
             mclBnGT_add(ref z, x, y);

ffi/cs/test/test.cs

@@ -210,6 +210,20 @@ namespace mcl {
                 Q.Deserialize(buf);
                 assert("P == Q", P.Equals(Q));
             }
+            {
+                const int n = 5;
+                G2[] xVec = new G2[n];
+                Fr[] yVec = new Fr[n];
+                P.Clear();
+                for (int i = 0; i < n; i++) {
+                    xVec[i].HashAndMapTo(i.ToString());
+                    yVec[i].SetByCSPRNG();
+                    Q.Mul(xVec[i], yVec[i]);
+                    P.Add(P, Q);
+                }
+                MulVec(ref Q, xVec, yVec);
+                assert("mulVecG2", P.Equals(Q));
+            }
         }
         static void TestPairing()
         {