用逆波兰表达式实现计算器功能的数学头文件及源文件.支持四则运算,括号,负号,三角函数,求余,求幂和阶乘.但未处理大数,所以数值大小有限.-Math header file and source file with Reverse Polish expression calculator function. Supports four operations, brackets, negative numbers, trigonometric functions, modulo exponentia