significand

以浮点形式返回x的有效数字。

接口定义

C interface：

float significandf(float x);

double significand(double x);

参数

参数名	类型	描述	输入/输出
x	在significandf中，x是单精度浮点类型。在significand中，x是双精度浮点类型。	表示输入数据的浮点值。	输入

返回值

返回x的有效数字，|y| ∈ [1, 2)。
输入+0，返回+0。
输入-0，返回-0。
输入±∞，返回±∞。
输入nan，返回nan。

依赖

C: "km.h"

示例

C interface：

    // typical usage
    double x1 = 0.0, x2 = -0.0, x3 = 1.5, x4 = -2.5, x5 = 0x1p-1024;
    // special handing
    double a = INFINITY, b = -INFINITY, c = NAN;
    // print result
    printf("significand(0.0) = %.15f\n", significand(x1));
    printf("significand(-0.0) = %.15f\n", significand(x2));
    printf("significand(1.5) = %.15f\n", significand(x3));
    printf("significand(-2.5) = %.15f\n", significand(x4));
    printf("significand(0x1p-1024) = %.15f\n", significand(x5));
    printf("significand(INFINITY) = %.15f\n", significand(a));
    printf("significand(-INFINITY) = %.15f\n", significand(b));
    printf("significand(NAN) = %.15f\n", significand(c));
    /* 
     * significand(0.0) = 0.000000000000000
     * significand(-0.0) = -0.000000000000000
     * significand(1.5) = 1.500000000000000
     * significand(-2.5) = -1.250000000000000
     * significand(0x1p-1024) = 1.000000000000000
     * significand(INFINITY) = inf
     * significand(-INFINITY) = -inf
     * significand(NAN) = nan
     * 
     * */

父主题： 杂项函数