diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5b18d87..dae8956 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,7 @@ set(NASAL_OBJECT_SOURCE_FILE
     ${CMAKE_SOURCE_DIR}/src/nasal_ast.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_builtin.cpp
     ${CMAKE_SOURCE_DIR}/src/fg_props.cpp
+    ${CMAKE_SOURCE_DIR}/src/math_lib.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_codegen.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_dbg.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_err.cpp
diff --git a/makefile b/makefile
index 7db2e34..636cd5f 100644
--- a/makefile
+++ b/makefile
@@ -17,7 +17,8 @@ NASAL_HEADER=\
 	src/nasal.h\
 	src/optimizer.h\
 	src/symbol_finder.h\
-	src/fg_props.h
+	src/fg_props.h\
+	src/math_lib.h
 
 NASAL_OBJECT=\
 	build/nasal_err.o\
@@ -35,6 +36,7 @@ NASAL_OBJECT=\
 	build/nasal_gc.o\
 	build/nasal_builtin.o\
 	build/fg_props.o\
+	build/math_lib.o\
 	build/nasal_vm.o\
 	build/nasal_dbg.o\
 	build/main.o
@@ -87,6 +89,12 @@ build/nasal_builtin.o: \
 	src/nasal_builtin.h src/nasal_builtin.cpp | build
 	$(CXX) -std=$(STD) -c -O3 src/nasal_builtin.cpp -fno-exceptions -fPIC -o build/nasal_builtin.o -I .
 
+build/math_lib.o: \
+	src/nasal.h\
+	src/nasal_gc.h\
+	src/math_lib.h src/math_lib.cpp | build
+	$(CXX) -std=$(STD) -c -O3 src/math_lib.cpp -fno-exceptions -fPIC -o build/math_lib.o -I .
+
 build/fg_props.o: \
 	src/nasal.h\
 	src/nasal_gc.h\
diff --git a/src/math_lib.cpp b/src/math_lib.cpp
new file mode 100644
index 0000000..ecda7cc
--- /dev/null
+++ b/src/math_lib.cpp
@@ -0,0 +1,73 @@
+#include "math_lib.h"
+
+var builtin_pow(var* local, gc& ngc) {
+    var x = local[1];
+    var y = local[2];
+    if (x.type!=vm_num || y.type!=vm_num) {
+        return var::num(std::nan(""));
+    }
+    return var::num(std::pow(x.num(), y.num()));
+}
+
+var builtin_sin(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?sin(val.num()):std::nan(""));
+}
+
+var builtin_cos(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?cos(val.num()):std::nan(""));
+}
+
+var builtin_tan(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?tan(val.num()):std::nan(""));
+}
+
+var builtin_exp(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?exp(val.num()):std::nan(""));
+}
+
+var builtin_lg(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?log(val.num())/log(10.0):std::nan(""));
+}
+
+var builtin_ln(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?log(val.num()):std::nan(""));
+}
+
+var builtin_sqrt(var* local, gc& ngc) {
+    var val = local[1];
+    return var::num(val.type==vm_num?sqrt(val.num()):std::nan(""));
+}
+
+var builtin_atan2(var* local, gc& ngc) {
+    var x = local[1];
+    var y = local[2];
+    if (x.type!=vm_num || y.type!=vm_num) {
+        return var::num(std::nan(""));
+    }
+    return var::num(atan2(y.num(), x.num()));
+}
+
+var builtin_isnan(var* local, gc& ngc) {
+    var x = local[1];
+    return (x.type==vm_num && std::isnan(x.num()))?one:zero;
+}
+
+nasal_builtin_table math_lib_native[] = {
+    {"__pow", builtin_pow},
+    {"__sin", builtin_sin},
+    {"__cos", builtin_cos},
+    {"__tan", builtin_tan},
+    {"__exp", builtin_exp},
+    {"__lg", builtin_lg},
+    {"__ln", builtin_ln},
+    {"__sqrt", builtin_sqrt},
+    {"__atan2", builtin_atan2},
+    {"__isnan", builtin_isnan},
+    {nullptr, nullptr}
+};
\ No newline at end of file
diff --git a/src/math_lib.h b/src/math_lib.h
new file mode 100644
index 0000000..2b9e1a4
--- /dev/null
+++ b/src/math_lib.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "nasal.h"
+#include "nasal_gc.h"
+#include "nasal_builtin.h"
+
+var builtin_pow(var*, gc&);
+var builtin_sin(var*, gc&);
+var builtin_cos(var*, gc&);
+var builtin_tan(var*, gc&);
+var builtin_exp(var*, gc&);
+var builtin_lg(var*, gc&);
+var builtin_ln(var*, gc&);
+var builtin_sqrt(var*, gc&);
+var builtin_atan2(var*, gc&);
+var builtin_isnan(var*, gc&);
+
+extern nasal_builtin_table math_lib_native[];
\ No newline at end of file
diff --git a/src/nasal_builtin.cpp b/src/nasal_builtin.cpp
index 4ceed8e..bf9b4a5 100644
--- a/src/nasal_builtin.cpp
+++ b/src/nasal_builtin.cpp
@@ -243,64 +243,6 @@ var builtin_u32not(var* local, gc& ngc) {
     return var::num((f64)(u32)(~u32(local[1].num())));
 }
 
-var builtin_pow(var* local, gc& ngc) {
-    var x = local[1];
-    var y = local[2];
-    if (x.type!=vm_num || y.type!=vm_num) {
-        return var::num(std::nan(""));
-    }
-    return var::num(std::pow(x.num(), y.num()));
-}
-
-var builtin_sin(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?sin(val.num()):std::nan(""));
-}
-
-var builtin_cos(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?cos(val.num()):std::nan(""));
-}
-
-var builtin_tan(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?tan(val.num()):std::nan(""));
-}
-
-var builtin_exp(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?exp(val.num()):std::nan(""));
-}
-
-var builtin_lg(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?log(val.num())/log(10.0):std::nan(""));
-}
-
-var builtin_ln(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?log(val.num()):std::nan(""));
-}
-
-var builtin_sqrt(var* local, gc& ngc) {
-    var val = local[1];
-    return var::num(val.type==vm_num?sqrt(val.num()):std::nan(""));
-}
-
-var builtin_atan2(var* local, gc& ngc) {
-    var x = local[1];
-    var y = local[2];
-    if (x.type!=vm_num || y.type!=vm_num) {
-        return var::num(std::nan(""));
-    }
-    return var::num(atan2(y.num(), x.num()));
-}
-
-var builtin_isnan(var* local, gc& ngc) {
-    var x = local[1];
-    return (x.type==vm_num && std::isnan(x.num()))?one:zero;
-}
-
 var builtin_time(var* local, gc& ngc) {
     var val = local[1];
     if (val.type!=vm_num) {
@@ -1306,16 +1248,6 @@ nasal_builtin_table builtin[] = {
     {"__u32or", builtin_u32or},
     {"__u32nand", builtin_u32nand},
     {"__u32not", builtin_u32not},
-    {"__pow", builtin_pow},
-    {"__sin", builtin_sin},
-    {"__cos", builtin_cos},
-    {"__tan", builtin_tan},
-    {"__exp", builtin_exp},
-    {"__lg", builtin_lg},
-    {"__ln", builtin_ln},
-    {"__sqrt", builtin_sqrt},
-    {"__atan2", builtin_atan2},
-    {"__isnan", builtin_isnan},
     {"__time", builtin_time},
     {"__contains", builtin_contains},
     {"__delete", builtin_delete},
diff --git a/src/nasal_builtin.h b/src/nasal_builtin.h
index d14d62d..85a8050 100644
--- a/src/nasal_builtin.h
+++ b/src/nasal_builtin.h
@@ -59,16 +59,6 @@ var builtin_u32and(var*, gc&);
 var builtin_u32or(var*, gc&);
 var builtin_u32nand(var*, gc&);
 var builtin_u32not(var*, gc&);
-var builtin_pow(var*, gc&);
-var builtin_sin(var*, gc&);
-var builtin_cos(var*, gc&);
-var builtin_tan(var*, gc&);
-var builtin_exp(var*, gc&);
-var builtin_lg(var*, gc&);
-var builtin_ln(var*, gc&);
-var builtin_sqrt(var*, gc&);
-var builtin_atan2(var*, gc&);
-var builtin_isnan(var*, gc&);
 var builtin_time(var*, gc&);
 var builtin_contains(var*, gc&);
 var builtin_delete(var*, gc&);
diff --git a/src/nasal_codegen.cpp b/src/nasal_codegen.cpp
index b3b7753..6d16310 100644
--- a/src/nasal_codegen.cpp
+++ b/src/nasal_codegen.cpp
@@ -14,6 +14,7 @@ void codegen::load_native_function_table(nasal_builtin_table* table) {
 
 void codegen::init_native_function() {
     load_native_function_table(builtin);
+    load_native_function_table(math_lib_native);
     load_native_function_table(flight_gear_native);
 }
 
diff --git a/src/nasal_codegen.h b/src/nasal_codegen.h
index 2e8ca94..fbfe11b 100644
--- a/src/nasal_codegen.h
+++ b/src/nasal_codegen.h
@@ -9,6 +9,7 @@
 #include "nasal_import.h"
 
 #include "nasal_builtin.h"
+#include "math_lib.h"
 #include "fg_props.h"
 
 #include <iomanip>
diff --git a/std/math.nas b/std/math.nas
index b3c7e1d..a19ea80 100644
--- a/std/math.nas
+++ b/std/math.nas
@@ -2,16 +2,29 @@
 # 2023 by ValKmjolnir
 # mostly used math functions and special constants, you know.
 
+# constant e
 var e = 2.7182818284590452354;
+
+# constant pi
 var pi = 3.14159265358979323846264338327950288;
 
+# maybe useless, just tell you
+# how to make inf and nan in IEEE754 double.
+# carefully using these two constants,
+# may cause critical error in calculation.
 var inf = 1/0;
+
+# nan can be created by (inf - inf) or (-inf + inf)
 var nan = 0/0;
 
 var abs = func(x) {
     return x>0? x:-x;
 }
 
+# floor will get the integral number of input argument
+# which is less than or equal to this argument.
+# this is basic native function in old nasal, 
+# but we think it should have a copy in math module.
 var floor = func(x) {
     return __floor(x);
 }