--- a
+++ b/matlab/isPos.m
@@ -0,0 +1,11 @@
+function b = isPos(X,Y,M,d)
+    for i=1:size(M,1)
+        r = (X-M(i,1))^2 + (Y-M(i,2))^2;
+        if r < d*d
+            b = true;
+            return 
+        end
+        b = false;
+        return
+    end
+end
\ No newline at end of file