计算x的平方根。

接口定义

C interface:

float sqrtf(float x);

double sqrt(double x);

Fortran interface:

RES = SQRTF(X);

RES = SQRT(X);

参数

参数名	类型	描述	输入/输出
x	在sqrtf中，x是单精度浮点类型。在sqrt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

输入x为±0，返回±0。
输入x为+∞，返回+∞。
输入x为nan，返回nan。

依赖

C: "km.h"

Fortran: "km.f03"

示例

C interface:

    // typical usage 
    double x1 = 1.0, x2 = 2.0, x3 = 3.0, x4 = 4.0; 
    // special handing 
    double a = 0.0, b = INFINITY, c = -INFINITY, d = NAN; 
    // print result 
        printf("sqrt(1.0) = %.15f\n", sqrt(x1)); 
        printf("sqrt(2.0) = %.15f\n", sqrt(x2)); 
        printf("sqrt(3.0) = %.15f\n", sqrt(x3)); 
        printf("sqrt(4.0) = %.15f\n", sqrt(x4)); 
        printf("sqrt(0.0) = %.15f\n", sqrt(a)); 
        printf("sqrt(INFINITY) = %.15f\n", sqrt(b)); 
        printf("sqrt(-INFINITY) = %.15f\n", sqrt(c)); 
        printf("sqrt(NAN) = %.15f\n", sqrt(d)); 
    /* 
     *  sqrt(1.0) = 1.000000000000000 
     *  sqrt(2.0) = 1.414213562373095 
     *  sqrt(3.0) = 1.732050807568877 
     *  sqrt(4.0) = 2.000000000000000 
     *  sqrt(0.0) = 0.000000000000000 
     *  sqrt(INFINITY) = inf 
     *  sqrt(-INFINITY) = -inf
     *  sqrt(NAN) = nan 
     * */

Fortran interface:

    REAL(8) :: X = 3.0 
    PRINT*,  SQRT(X) 
    ! 
    ! OUTPUT 
    !     1.732050807568877 
    !