add tan function in Array world
diff --git a/doc/snippets/Cwise_tan.cpp b/doc/snippets/Cwise_tan.cpp
new file mode 100644
index 0000000..b758ef0
--- /dev/null
+++ b/doc/snippets/Cwise_tan.cpp
@@ -0,0 +1,2 @@
+Array3d v(M_PI, M_PI/2, M_PI/3);
+cout << v.tan() << endl;