Add cswap function

`cswap` "swaps" the real and imaginary components of a complex tensor)

src/arraymancer/tensor/complex.nim

@@ -92,3 +92,7 @@ proc conjugate*[T: Complex32 | Complex64](A: Tensor[T]): Tensor[T] =
   ## Return the element-wise complex conjugate of a tensor of complex numbers.
   ## The complex conjugate of a complex number is obtained by changing the sign of its imaginary part.
   A.map_inline(x.conjugate)
+
+proc cswap*[T: Complex32 | Complex64](t: Tensor[T]): Tensor[T] {.inline, noinit.} =
+  ## Swap the real and imaginary components of the elements of a complex Tensor
+  map_inline(t, complex(x.im, x.re))

tests/tensor/test_complex.nim

@@ -121,5 +121,20 @@ proc main() =
 
       check: c.conjugate == expected_c_conjugate
 
+    test "Complex Component Swap":
+      var c = [
+        complex(1.0, -300.0),
+        complex(-10.0, 20.0),
+        complex(20.0, -1.0),
+      ].toTensor
+
+      var expected_c_swapped = [
+        complex(-300.0, 1.0),
+        complex(20.0, -10.0),
+        complex(-1.0, 20.0),
+      ].toTensor
+
+      check: c.cswap == expected_c_swapped
+
 main()
 GC_fullCollect()