change id name & add test file

test/bp.nas

@@ -137,7 +137,7 @@ while(error>0.001)
     }
     cnt+=1;
     show+=1;
-    if(show==150)
+    if(show==200)
     {
         show=0;
         print('epoch ',cnt,':',error,'\r');

test/pi.nas

@@ -0,0 +1,10 @@
+import("lib.nas");
+
+var t=1;
+var res=0;
+for(var m=1;m<1e6;m+=2)
+{
+    res+=t*1/m;
+    t*=-1;
+}
+println(res*4);