各种数值积分，包括牛顿积分，辛普生各分、龙贝格积分,高斯积分和高斯—勒让德积分-A variety of numerical integration, including Newton integral, sub Simpson, Romberg integration, Gaussian integrals and Gauss- Legendre integration

利用Fortran语言编写高斯消元法来求解多元函数方程-Gaussian Elimination