diff --git a/README.md b/README.md
index d70c5be..7b31eda 100644
--- a/README.md
+++ b/README.md
@@ -23,21 +23,10 @@ abs[-1] + 2^3 = 9
 sin(90) + 5 = 5.893996663600558
 (PI - 1) * 3 = 6.424777960769379
 PI + 1 + 10%3 = 5.141592653589793
-```
 
-## prefix
-```
-+ 1 -5 = -4
-+ -1 5 = 4
-+ -1 -5 = -6
-+ abs[-1] 2 = 3
-+ abs[-1] 2^3 = 9
-+ - -1 |-3| 2^5 = 28
-+ - -10 abs(-3) 2^5 = 18
-+ - -1 abs(-3) pow[2, 5] = 28
-+ sin(90) 5 = 5.893996663600558
-* - PI 1 3 = 6.424777960769379
-+ + PI 1 10%3 = 5.141592653589793
+pow(5,|1 - 4|) = 125
+max(10, 20 + 5, 30 - 40, min ( 40, 100)) = 40
+max(10, 20 + 5, min ( 40, 100) * 4,30 - 40) = 160
 ```
 
 ## postfix
@@ -53,6 +42,29 @@ abs[-1] 2^3 + = 9
 sin(90) 5 + = 5.893996663600558
 PI 1 - 3 * = 6.424777960769379
 PI 1 + 10%3 + = 5.141592653589793
+
+. 5 . 1 3 - abs. pow. = 25
+. 10 20 5 + 30 40 - . 40 100 min. max. = 40
+. 10 20 5 + . 40 100 min. 4 * 30 40 - max. = 160
+```
+
+## prefix
+```
++ 1 -5 = -4
++ -1 5 = 4
++ -1 -5 = -6
++ abs[-1] 2 = 3
++ abs[-1] 2^3 = 9
++ - -1 |-3| 2^5 = 28
++ - -10 abs(-3) 2^5 = 18
++ - -1 abs(-3) pow[2, 5] = 28
++ sin(90) 5 = 5.893996663600558
+* - PI 1 3 = 6.424777960769379
++ + PI 1 10%3 = 5.141592653589793
+
+.pow 5 .abs - 1 4 . . = 125
+.max 10 + 20 5 - 30 40 .min 40 100 . . = 40
+.max 10 + 20 5 * .min 40 100 . 4 - 30 40 . = 160
 ```
 
 # Installation
diff --git a/package.json b/package.json
index bcbc5df..321e1d2 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,6 @@
   },
   "scripts": {
     "start": "node cli.js",
-    "stop": "tape test/2-postfixer.js | faucet",
     "test": "standard && tape test/*.js | faucet"
   },
   "repository": {
diff --git a/postfixer.js b/postfixer.js
index 19cae95..9bc452d 100644
--- a/postfixer.js
+++ b/postfixer.js
@@ -49,7 +49,7 @@ exports = module.exports = function toPostfixNotation (exp) {
   // 3. after an operator
   var nega = true
   // skip handle when meet Math's functions
-  var skip = null
+  var skip = []
 
   var token = ''
   for (var i = 0, j = exp.length; i < j; i++) {
@@ -58,8 +58,8 @@ exports = module.exports = function toPostfixNotation (exp) {
     if (cur === SPACE) continue
 
     // handle Math's functions
-    if (skip) {
-      if (cur === MATH_EXTEND[skip]) {
+    if (skip.length > 0) {
+      if (cur === MATH_EXTEND[skip[skip.length - 1]]) {
         removeFunction()
         continue
       } else if (cur === ',') {
@@ -137,22 +137,27 @@ exports = module.exports = function toPostfixNotation (exp) {
     if (!token) token = 'abs'
     stack.push(token + MATH_EP)
     token = ''
-    skip = cur
+    skip.push(cur)
   }
 
   function removeFunction () {
-    out.push(token)
+    if (token) {
+      out.push(token)
+      token = ''
+    }
     while (stack.length > 0) {
       var o = stack.pop()
       out.push(o)
       if (o.substr(o.length - MATH_EP.length) === MATH_EP) break
     }
-    token = ''
-    skip = null
+    skip.pop()
   }
 
   function removeComma () {
-    out.push(token)
+    if (token) {
+      out.push(token)
+      token = ''
+    }
     while (stack.length > 0) {
       var o = stack.pop()
       if (o.substr(o.length - MATH_EP.length) === MATH_EP) {
@@ -162,7 +167,6 @@ exports = module.exports = function toPostfixNotation (exp) {
         out.push(o)
       }
     }
-    token = ''
   }
 
   function enableNega () {
diff --git a/test/2-postfixer.js b/test/2-postfixer.js
index 47e7b4b..eefaee9 100644
--- a/test/2-postfixer.js
+++ b/test/2-postfixer.js
@@ -31,22 +31,13 @@ test('infix to postfix test', function (t) {
 
 test('func: infix to postfix test', function (t) {
   t.equal(postfixer('abs(1 - 2)'), '. 1 2 - abs.')
+  t.equal(postfixer('|1 - 2|'), '. 1 2 - abs.')
+  t.equal(postfixer('pow(5,|1 - 2|)'), '. 5 . 1 2 - abs. pow.')
   t.equal(postfixer('min(10, 20, 30)'), '. 10 20 30 min.')
   t.equal(postfixer('max(10, 20 + 5, 30 - 40)'), '. 10 20 5 + 30 40 - max.')
-  // t.equal(postfixer('1 + 2 * 3'), '1 2 3 * +')
-  // t.equal(postfixer('(1 + 2) * 3'), '1 2 + 3 *')
-  // t.equal(postfixer('(abs[1] + 2) * 3 + E'), 'abs[1] 2 + 3 * E +')
-  // t.equal(postfixer('(PI     + 2) * 3 + E'), 'PI 2 + 3 * E +')
-  // t.equal(postfixer('(PI     + 2/ 10) * 3 + (E-19 )'), 'PI 2 10 / + 3 * E 19 - +')
-  // t.equal(postfixer('(1 + 2 - 3*(PI + 10))'), '1 2 + 3 PI 10 + * -')
-  //
-  // t.equal(postfixer('1 + (-2)'), '1 -2 +')
-  // t.equal(postfixer('-1 + 2 + -3'), '-1 2 + -3 +')
-  // t.equal(postfixer('1 + - 2'), '1 -2 +')
-  // t.equal(postfixer('-1 + - 2'), '-1 -2 +')
-  // t.equal(postfixer('-1 - -3'), '-1 -3 -')
-  // t.equal(postfixer('|-1| - -3'), '|-1| -3 -')
-  // t.equal(postfixer('abs[-1] - -3'), 'abs[-1] -3 -')
+
+  t.equal(postfixer('max(10, 20 + 5, 30 - 40, min ( 40, 100))'), '. 10 20 5 + 30 40 - . 40 100 min. max.')
+  t.equal(postfixer('max(10, 20 + 5, min ( 40, 100) * 4,30 - 40)'), '. 10 20 5 + . 40 100 min. 4 * 30 40 - max.')
 
   t.end()
 })
diff --git a/test/4-func.js b/test/4-func.js
index 3ad24a7..ed82dba 100644
--- a/test/4-func.js
+++ b/test/4-func.js
@@ -14,6 +14,15 @@ test('func - postfix test', function (t) {
 
   t.equal(app('. 2 . 2 3 pow. - max.'), -6)
 
+  t.equal(app('. 1 2 - abs.'), 1)
+  t.equal(app('. 1 2 - abs.'), 1)
+  t.equal(app('. 5 . 1 3 - abs. pow.'), 25)
+  t.equal(app('. 10 20 30 min.'), 10)
+  t.equal(app('. 10 20 5 + 30 40 - max.'), 25)
+
+  t.equal(app('. 10 20 5 + 30 40 - . 40 100 min. max.'), 40)
+  t.equal(app('. 10 20 5 + . 40 100 min. 4 * 30 40 - max.'), 160)
+
   t.end()
 })
 
@@ -30,3 +39,16 @@ test('func - prefix test', function (t) {
 
   t.end()
 })
+
+test('func - infix test', function (t) {
+  t.equal(app('abs(1 - 2)'), 1)
+  t.equal(app('|1 - 2|'), 1)
+  t.equal(app('pow(5,|1 - 4|)'), 125)
+  t.equal(app('min(10, 20, 30)'), 10)
+  t.equal(app('max(10, 20 + 5, 30 - 40)'), 25)
+
+  t.equal(app('max(10, 20 + 5, 30 - 40, min ( 40, 100))'), 40)
+  t.equal(app('max(10, 20 + 5, min ( 40, 100) * 4,30 - 40)'), 160)
+
+  t.end()
+})