funtions to calculate the simple, double and triple integrals

使用高斯、复合梯形、复合辛普生求解二重积分（矩形求积区域和三角型求积区域）的数值计算方法，使用C语言。-Use Gaussian composite trapezoidal composite Simpson solving double integrals (Rectangular Quadrature region and the triangular the Quadrature area), numerical methods, the use of the C language.

用Romberg算法计算定积分 #include <stdio.h> #include <math.h> #define MAX 10 double func(double a) { double y if (a == 0) return y = 1 else return y = 4/(1+a*a) //return y = pow(a,2) }-Romberg algorithm computes