y0

接口定义

C interface：

float y0f(float x);

double y0(double x);

参数

返回值

• 返回以0阶第二类贝塞尔函数值y，y ∈ (-∞, +1)。
• 输入x为±0，返回-∞。
• 输入x<0，返回nan。
• 输入x为+∞，返回0。
• 输入x为nan，返回nan。

依赖

C: "km.h"

示例

C interface：

    double x1 = 0.0, x2 = -0.0, x3 = 1.5, x4 = -2.5;
    // special handing
    double a = INFINITY, b = -INFINITY, c = NAN;
    // print result
    printf("y0(0.0) = %.15f\n", y0(x1));
    printf("y0(-0.0) = %.15f\n", y0(x2));
    printf("y0(1.5) = %.15f\n", y0(x3));
    printf("y0(-2.5) = %.15f\n", y0(x4));
    printf("y0(INFINITY) = %.15f\n", y0(a));
    printf("y0(-INFINITY) = %.15f\n", y0(b));
    printf("y0(NAN) = %.15f\n", y0(c));

    /* 
     * y0(0.0) = -inf
     * y0(-0.0) = -inf
     * y0(1.5) = 0.382448923797759
     * y0(-2.5) = nan
     * y0(INFINITY) = 0.000000000000000
     * y0(-INFINITY) = nan
     * y0(NAN) = nan
     * 
     * */