变系数抛物方程 用最简显格式、紧格式、Keller盒式格式求近似解和误差 -Parabolic equations with variable coefficients were the most simple form, tight format, Keller cassette format, the approximate solution and error

一个小软件，初学者可看看，做的是用海伦凯勒公式计算的三角形面积软件-A small software, beginners can take a look, do the Helen Keller formula to calculate the triangle area of ​ ​ software