Updated README.md implementation

README.md

@@ -1,2 +1,54 @@
 # MathJs Wrapper
 A wrapper of the mathjs.org (https://mathjs.org/) JavaScript library for Android to evaluate math expressions.
+
+## Implementation
+
+#### Initialization
+
+Initialize MathJsWapper object with context.
+```
+var mathJsWrapper = MathJsWrapper(this)
+```
+
+#### Evaluate Expressions
+
+1. Various supported expressions
+
+```
+val expression = "12 / (2.3 + 0.7)" // 2.718
+val expression = "12.7 cm to inch" // 5 inch
+val expression = "sin(45 deg) ^ 2" // 0.5
+val expression = "9 / 3 + 2i" // 3 + 2i
+val expression = "det([-1, 2; 3, 1])" // -7
+val expression = "111111111111111111111111111111111111111111111111+2222222222222222222222222222222222222222222222222" // 2.3333333e+48
+
+
+val output: String = mathJsWrapper.eval(expression)
+```
+
+2. Various supported expressions with variables
+
+```
+val expression = "a / (b + c)" // 2.718
+val map = HashMap<String, Any>()
+map["a"] = 12
+map["b"] = 2.3
+map["c"] = 0.7
+
+val output: String = mathJsWrapper.eval(expression, map)
+```
+
+#### Traverse specified node of Expressions
+
+You can get all the nodes from expressions such as 'SymbolNode', 'OperatorNode', 'ConstantNode', 'ParenthesisNode'
+```
+val expression = "a / (b + c)" // 2.718
+val list = mathJsWrapper.getExpressionNodes(expression, NodeType.SymbolNode) // ["a","b","c"]
+```
+
+#### Remove MathJsWapper in `onDestroy()`
+
+Deallocate instances after being used.
+```
+mathJsWrapper.onDestroy()
+```