Added complex example for article

examples/src/main/kotlin/scientifik/kmath/structures/ComplexND.kt

@@ -1,5 +1,8 @@
 package scientifik.kmath.structures
 
+import scientifik.kmath.linear.transpose
+import scientifik.kmath.operations.Complex
+import scientifik.kmath.operations.toComplex
 import kotlin.system.measureTimeMillis
 
 fun main() {
@@ -32,3 +35,23 @@ fun main() {
 
     println("Complex addition completed in $complexTime millis")
 }
+
+
+fun complexExample() {
+    //Create a context for 2-d structure with complex values
+    NDField.complex(4, 8).run {
+        //a constant real-valued structure
+        val x = one * 2.5
+        operator fun Number.plus(other: Complex) = Complex(this.toDouble() + other.re, other.im)
+        //a structure generator specific to this context
+        val matrix = produce { (k, l) ->
+            k + l*i
+        }
+
+        //Perform sum
+        val sum = matrix + x + 1.0
+
+        //Represent the sum as 2d-structure and transpose
+        sum.as2D().transpose()
+    }
+}