y1

Interface Definition

C interface:

float y1f(float x);

double y1(double x);

Parameters

Return Value

• The order-1 second-kind Bessel function value y is returned. y ∈ (–∞, +1).
• If the input x is ±0, the return value is –∞.
• If the input x is less than 0, the return value is NaN.
• If the input x is +∞, the return value is 0.
• If the input x is NaN, the return value is NaN.

Dependency

C: "km.h"

Example

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("y1(0.0) = %.15f\n", y1(x1));
    printf("y1(-0.0) = %.15f\n", y1(x2));
    printf("y1(1.5) = %.15f\n", y1(x3));
    printf("y1(-2.5) = %.15f\n", y1(x4));
    printf("y1(INFINITY) = %.15f\n", y1(a));
    printf("y1(-INFINITY) = %.15f\n", y1(b));
    printf("y1(NAN) = %.15f\n", y1(c));

    /* 
     * y1(0.0) = -inf
     * y1(-0.0) = -inf
     * y1(1.5) = -0.412308626973911
     * y1(-2.5) = nan
     * y1(INFINITY) = 0.000000000000000
     * y1(-INFINITY) = nan
     * y1(NAN) = nan
     * 
     * */