diff --git a/balloon/abstract_syntax_tree.cpp b/balloon/abstract_syntax_tree.cpp
index 6b360be..adf3461 100644
--- a/balloon/abstract_syntax_tree.cpp
+++ b/balloon/abstract_syntax_tree.cpp
@@ -892,11 +892,6 @@ int abstract_syntax_tree::run_block()
 				++j;
 				if(j!=i->children.end())
 					new_var=j->calculation();
-				if(new_var.get_type()==__var_function)
-				{
-					exit_type=__bad_definition;
-					std::cout<<">>[Runtime-error] line "<<line<<": cannot declare a function in any blocks."<<std::endl;
-				}
 				new_var.set_name(_name);
 				scope.add_new_var(new_var);
 			}
diff --git a/balloon/balloon_type.h b/balloon/balloon_type.h
index 9308b46..49536a5 100644
--- a/balloon/balloon_type.h
+++ b/balloon/balloon_type.h
@@ -175,7 +175,6 @@ enum runtime_error_type
 	__find_var_failure,
 	__error_value_type,
 	__error_command_use,
-	__bad_definition,
 	__sigfpe_arithmetic_exception,
 	__sigsegv_segmentation_error,
 	__terminal_interrupt,
@@ -193,7 +192,6 @@ void print_exit_type(int type)
 		case __find_var_failure:            context="find_var_failure";break;
 		case __error_value_type:            context="value_type_error";break;
 		case __error_command_use:           context="command_use_error(continue/break/return)";break;
-		case __bad_definition:              context="bad_definition(func in block)";break;
 		case __sigfpe_arithmetic_exception: context="SIGFPE_arithmetic_exception";break;
 		case __sigsegv_segmentation_error:  context="SIGSEGV_segmentation_error";break;
 		case __terminal_interrupt:          context="interrupt";break;
diff --git a/balloon/lib/math.nas b/balloon/lib/math.nas
index 77a3b99..d7823f2 100644
--- a/balloon/lib/math.nas
+++ b/balloon/lib/math.nas
@@ -8,15 +8,14 @@ var abs=func(__x)
     else{return -__x;}
 };
 
-var __balloon_lib_ln_asr=func(__x,__y)
-{
-    if(abs(__y-__x)<=0.1){return (1/__x+8/(__x+__y)+1/__y)*(__y-__x)/6;}
-    var __mid=(__x+__y)/2;
-    return __balloon_lib_ln_asr(__x,__mid)+__balloon_lib_ln_asr(__mid,__y);
-};
-
 var ln=func(_x)
 {
+    var __balloon_lib_ln_asr=func(__x,__y)
+    {
+        if(abs(__y-__x)<=0.1){return (1/__x+8/(__x+__y)+1/__y)*(__y-__x)/6;}
+        var __mid=(__x+__y)/2;
+        return __balloon_lib_ln_asr(__x,__mid)+__balloon_lib_ln_asr(__mid,__y);
+    };
     return __balloon_lib_ln_asr(1,_x);
 };
 
@@ -113,20 +112,19 @@ var sqrt=func(__x)
     return t;
 };
 
-var __balloon_lib_asin_asr=func(__x,__y)
+var asin=func(_x)
 {
-    var __mid=(__x+__y)/2;
-    if(abs(__y-__x)<=0.01){return (1/sqrt(1-__x*__x)+4/sqrt(1-__mid*__mid)+1/sqrt(1-__y*__y))*(__y-__x)/6;}
-    return __balloon_lib_asin_asr(__x,__mid)+__balloon_lib_asin_asr(__mid,__y);
-};
-
-var asin=func(__x)
-{
-    if(abs(__x)>1){return -1;}
+    var __balloon_lib_asin_asr=func(__x,__y)
+    {
+        var __mid=(__x+__y)/2;
+        if(abs(__y-__x)<=0.01){return (1/sqrt(1-__x*__x)+4/sqrt(1-__mid*__mid)+1/sqrt(1-__y*__y))*(__y-__x)/6;}
+        return __balloon_lib_asin_asr(__x,__mid)+__balloon_lib_asin_asr(__mid,__y);
+    };
+    if(abs(_x)>1){return -1;}
     var fl=1;
-    if(__x<0){fl=-fl;__x=-__x;}
-    if(abs(__x-1)<0.001){return pi/2;}
-    return fl*__balloon_lib_asin_asr(0,__x);
+    if(_x<0){fl=-fl;_x=-_x;}
+    if(abs(_x-1)<0.001){return pi/2;}
+    return fl*__balloon_lib_asin_asr(0,_x);
 };
 
 var acos=func(__x)