算法-->1，2维多项式

以你之姓@ 2022-06-11 03:52 154阅读 0赞

package 多项式计算;
    
    import java.text.DecimalFormat;
    
    public class YiWei {
        static double yiwei(double a[], int n, double x) {
            int i;
            double result;
            result = a[n - 1];
            for (i = n - 2; i >= 0; i--) {
                // 递推关系运算
                result = result * x + a[i];
            }
            return result;
        }
    
        public static void main(String[] args) {
            YiWei yi = new YiWei();
            int i;
            double a[] = { -15.0, -7.0, 7.0, 2.0, -3.0, 7.0, 3.0 };
            double[] x = { -2.0, -0.5, 1.0, 2.0, 3.7, 4.0 };
            double result;
            DecimalFormat ff = new DecimalFormat("0.0000000E000");
            DecimalFormat df = new DecimalFormat("0.00");
            System.out.print("\n");
            for (i = 0; i < 6; i++) {
                result = yiwei(a, 7, x[i]);
                System.out.print("x=" + df.format(x[i]) + "时，p(x)=" + ff.format(result) + "\n");
            }
            System.out.print("\n");
    
        }
    }

![这里写图片描述][SouthEast]

package 多项式计算;
    
    import java.text.DecimalFormat;
    
    public class ErWei {
        static double two(double d[][], int m, int n, double x, double y) {
            int i, j;
            double result, temp, tt;
            result = 0.0;
            tt = 1.0;
            // 递推求值,m和n分别 是自变量x,y多项式的项数，数组b是二项式的系数
            for (i = 0; i < m; i++) {
                temp = d[i][n - 1] * tt;
                for (j = n - 2; j >= 0; j--) {
                    temp = temp * y + d[i][j] * tt;
                }
                result += temp;
                tt *= x;
            }
            return result;
        }
    
        public static void main(String[] args) {
            ErWei ee = new ErWei();
            double result;
            double x, y;
            DecimalFormat df = new DecimalFormat("0.000E000");
            // 初始化二维多项式的系数
            double a[][] = { { 1.0, 2.0, 3.0, 4.0, 5.0 }, { 6.0, 7.0, 8.0, 9.0, 10.0 }, { 11.0, 12.0, 13.0, 14.0, 15.0 },
                    { 16.0, 17.0, 18.0, 19.0, 20.0 } };
            // 待求的点
            x = 0.5;
            y = -2.0;
            System.out.print("二维多项式求值：\n");
            result = two(a, 4, 5, x, y);
            System.out.print("p(" + x + "," + y + ")=" + df.format(result) + "\n");
            System.out.print("\n");
        }
    }

![这里写图片描述][SouthEast 1]

[SouthEast]: /images/20220611/53bb3f96969b4f27a125995fe237abad.png
[SouthEast 1]: /images/20220611/2aa869f14ab04acc8b4e29d284c66e33.png