计算方法之用追赶法求线性方程组

/************************************** 用追赶法求线性方程组* * |-             -| |-  -|   |-  -|* | 2  -1         | | x1 |   |  3 |* |-1   3  -2     | | x2 |   |  1 |* |    -2   4  -2 |*| x3 | = |  0 |* |        -2   5 | | x4 |   | -5 |* |-             -| |-  -|   |-  -|***************************************/#include<stdio.h>#include<math.h>#include<conio.h>#include<string.h>#include<stdlib.h>#define n 5int main() {float a[n] = { 0, 0, -1, -2, -2 };float b[n] = { 0, 2, 3, 4, 5 };float c[n] = { 0, -1, -2, -2, 0 };float d[n] = { 0, 3, 1, 0, -5 };float x[n] = { 0, 0, 0, 0, 0 };float r[n] = { 0, 0, 0, 0, 0 };float y[n] = { 0, 0, 0, 0, 0 };float q;int k;r[1] = c[1] / b[1];y[1] = d[1] / b[1];for (k = 2; k < n - 1; k++) {q = b[k] - r[k - 1] * a[k];r[k] = c[k] / q;y[k] = (d[k] - y[k - 1] * a[k]) / q;}y[n - 1] = (d[n - 1] - y[n - 2] * a[n - 1])/ (b[n - 1] - r[n - 2] * a[n - 1]);x[n - 1] = y[n - 1];for (k = n - 2; k >= 1; k--)x[k] = y[k] - r[k] * x[k + 1];for (k = 1; k < n; k++)printf("x[%d] = %f\n", k, x[k]);return 0;}