tanh

接口定义

C interface：

float tanhf(float x);

double tanh(double x);

long double tanhl(long double x);

Fortran interface：

RES = TANHF(X)

RES = TANH(X)

参数

返回值

• 返回弧度角x的双曲正切函数值y = sinh(x) / cosh(x)，y ∈ [-1, +1]。
• 输入+0，返回+0。
• 输入-0，返回-0。
• 输入+∞，返回+1。
• 输入-∞，返回-1。
• 输入nan，返回nan。

依赖

C: "km.h"

示例

C interface：

    double pi = acos(-1); 
    // typical usage 
    double a = pi/3, c = -3*pi/4, d = 0.0; 
    // special handling 
    double b = pi/2, e = INFINITY, f = -INFINITY, g = NAN; 
    // print result 
    printf("tanh(pi/3) = %.15f\n", tanh(a)); 
    printf("tanh(-3*pi/4) = %.15f\n", tanh(c)); 
    printf("tanh(0.0) = %.15f\n", tanh(d)); 
    // mathematical poles 
    printf("tanh(pi/2) = %.15f\n", tanh(b)); 
    printf("tanh(INFINITY) = %.15f\n", tanh(e)); 
    printf("tanh(-INFINITY) = %.15f\n", tanh(f)); 
    printf("tanh(NAN) = %.15f\n", tanh(g)); 
    /* 
     *  tanh(pi/3) = 0.780714435359268 
     *  tanh(-3*pi/4) = -0.982193380007239 
     *  tanh(0.0) = 0.000000000000000 
     *  tanh(pi/2) = 0.917152335667274 
     *  tanh(INFINITY) = 1.000000000000000
     *  tanh(-INFINITY) = -1.000000000000000
     *  tanh(NAN) = nan 
     * 
     * */

Fortran interface：

    REAL(8) :: X = 0.0 
    PRINT*,  TANH(X) 
    ! 
    ! OUTPUT 
    !     0.000000000000000 
    !