j1

接口定义

C interface：

float j1f(float x);

double j1(double x);

参数

返回值

• 返回以1阶第一类贝塞尔函数值y，y ∈ (-1, +1)，该函数为奇函数。
• 输入x为+0，返回+0。
• 输入x为-0，返回-0。
• 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("j1(0.0) = %.15f\n", j1(x1));
    printf("j1(-0.0) = %.15f\n", j1(x2));
    printf("j1(1.5) = %.15f\n", j1(x3));
    printf("j1(-2.5) = %.15f\n", j1(x4));
    printf("j1(INFINITY) = %.15f\n", j1(a));
    printf("j1(-INFINITY) = %.15f\n", j1(b));
    printf("j1(NAN) = %.15f\n", j1(c));

    /* 
     * j1(0.0) = 0.000000000000000
     * j1(-0.0) = -0.000000000000000
     * j1(1.5) = 0.557936507910100
     * j1(-2.5) = -0.497094102464274
     * j1(INFINITY) = 0.000000000000000
     * j1(-INFINITY) = 0.000000000000000
     * j1(NAN) = nan
     * 
     * */