asin() 函数在 math.h 头文件中定义。它有助于返回给定数字的弧度制反正弦值。反正弦表示 反正弦值。
double asin(double x); #where x can be in int, float or long double
此外，还使用了 asinf() 和 asinl() 两个函数，分别对应 float 和 long double 类型。
float asinf(float x);
long double asinl(long double x);
asin() 函数接受一个介于 1 ≥ x ≥ -1 之间的单个参数。我们可以使用类型转换运算符将类型显式转换为 double，以查找 int、float 或 long double 类型的反正弦。
| 参数 | 描述 | 必需/可选 |
|---|---|---|
| 双精度浮点数值 | 一个介于 -1 和 +1 之间的双精度值 | 必需 |
asin() 函数的返回值范围在 [-π/2, +π/2] 弧度之间。
| 输入 | 返回值 |
|---|---|
| x = [-1, +1] | [-π/2, +π/2] 弧度 |
| -1 > x 或 x > 1 | NaN (非数字) |
#include <stdio.h>
#include <math.h>
int main()
{
const double PI = 3.1415926;
double v, output;
v = -0.5;
output = asin(v);
printf("The Inverse of sin(%.2f) = %.2lf in radians\n", v, output);
//radians to degree convertion
output = asin(v)*180/PI;
printf("The Inverse of sin(%.2f) = %.2lf in degrees\n", v, output);
// paramter not in range
v = 1.2;
output = asin(v);
printf("The Inverse of sin(%.2f) = %.2lf", v, output);
return 0;
}
输出
The Inverse of sin(-0.50) = -0.52 in radians The Inverse of sin(-0.50) = -30.00 in degrees the Inverse of sin(1.20) = nan
#include <stdio.h>
#include <math.h>
int main()
{
float f, fsinx;
long double l, lsinx;
// type float
f = -0.505405;
fsinx = asinf(f);
//type long double
l = -0.50540593;
lsinx = asinl(l);
printf("asinf(x) is equal to %f in radians\n", fsinx);
printf("asinl(x) is equal to %Lf in radians", lsinx);
return 0;
}
输出
asinf(x) is equal to -0.529851 in radians asinl(x) is equal to -0.529852 in radians
