the last commit for lab6 exercises and a2 exercises

b4_3.m

@@ -0,0 +1,13 @@
+% 定义x,y
+x=6
+y=6
+if (x>=0 && y>=0)
+    r=x+y
+elseif (x>=0 && y<0)
+    r=x+y^2;
+elseif (x<0 && y>=0)
+    r=x^2+y;
+elseif (x<0 && y<0)
+    r=x^2+y^2;
+end
+disp(x)