Simple command line calculator. Supports arithmetic expressions, including operators, functions and parentheses. Supported operations: add(+), subtract(-), divide(/), multiply(*), modulus(%), power(^) Supported functions: sine(sin), cosine(cos), tan, log Known issues: 1. No support for negation operator (unary minus). As a work-around, use 0 - n instead of -n. For example, instead of -2^2, use (0-2)^2 Implementation outline: 1. Accept input from command prompt, in in-fix notation 2. Parse input into tokens 3. Convert tokens into post-fix notation, using shunting yard algorithm 4. Build a Binary Expression Tree from post-fix tokens 5. Evaluate expression by traversing Binary Expression Tree 6. Print result to command prompt and repeat on a loop