acosd

接口定义

C interface：

float acosdf(float x);

double acosd(double x);

long double acosdl(long double x);

参数

返回值

• 返回输入x的反余弦函数值对应的角度y=acos(x) * 180 / π，y ∈ [0, 180]。
• 输入+0，返回90。
• 输入-0，返回90。
• 输入x为1，返回+0。
• 输入x为-1，返回180。
• 输入|x|>1，返回nan。
• 输入±∞，返回nan。
• 输入nan，返回nan。

依赖

C： "km.h"

示例

C interface：

    // typical usage
    float x1 = -1.0, x2 = 1.0, x3 = 0.5, x4 = -0.5;
    float a = 0.0, b = INFINITY, c = -INFINITY, d = NAN;
    // print result
    printf("acosdf(1.0) = %.15f\n", acosdf(x1));
    printf("acosdf(-1.0) = %.15f\n", acosdf(x2));
    printf("acosdf(0.5) = %.15f\n", acosdf(x3));
    printf("acosdf(-0.5) = %.15f\n", acosdf(x4));
    printf("acosdf(0.0) = %.15f\n", acosdf(a));
    printf("acosdf(-0.0) = %.15f\n", acosdf(-a));
    printf("acosdf(INFINITY) = %.15f\n", acosdf(b));
    printf("acosdf(-INFINITY) = %.15f\n", acosdf(c));
    printf("acosdf(NAN) = %.15f\n", acosdf(d));
    /* 
     * acosdf(1.0) = 180.000000000000000
     * acosdf(-1.0) = 0.000000000000000
     * acosdf(0.5) = 60.000000000000000
     * acosdf(-0.5) = 120.000000000000000
     * acosdf(0.0) = 90.000000000000000
     * acosdf(-0.0) = 90.000000000000000
     * acosdf(INFINITY) = nan
     * acosdf(-INFINITY) = nan
     * acosdf(NAN) = nan
     * 
     * */