常用数学函数
计算反正弦 (arcsin(x))
std::asin,
std::asinf,
std::asinl
定义于头文件 | ||
float asinf( float arg ); | (1) | (C99 起) |
double asin( double arg ); | (2) | |
long double asinl( long double arg ); | (3) | (C99 起) |
定义于头文件 | ||
#define asin( arg ) | (4) | (C99 起) |
1-3) 计算 arg
的弧(反)正弦主值。
4) 泛型宏:若参数拥有 long double 类型,则调用 asinl
。否则,若参数拥有整数类型或 double 类型,则调用 asin
。否则调用 asinf
。若参数为复数,则宏调用对应的复数函数( casinf 、 casin 、 casinl )。
参数
arg | - | 浮点值 |
返回值
若不出现错误,则返回 arg
在范围 [-
π |
2 |
; +
π |
2 |
] 中的弧(反)正弦( arcsin(arg) )。
若出现定义域错误,则返回实现定义值(受支持平台上为 NaN )。
若出现下溢所致的值域错误,则返回(舍入后的)正确结果。
错误处理
报告 math_errhandling 中指定的错误。
若 arg
在范围 [-1.0; 1.0]
外则出现定义域错误。
若实现支持 IEEE 浮点算术( IEC 60559 ),则
- 若参数为 ±0 ,则返回不修改的参数。
- 若 |arg| > 1 ,则出现定义域错误并返回 NaN 。
- 若参数为 NaN ,则返回 NaN 。
调用示例
#include <iostream>
#include <cstdlib>
#include <typeinfo>
#include <cinttypes>
#include <cmath>
#include <math.h>
#include <tgmath.h>int main()
{//1-3) 计算 arg 的弧(反)正弦主值。const float fNumber = std::acos(-1);std::cout << "typeid(float).name(): " << typeid(float).name() << std::endl;for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << fNumber / i << "): "<< std::asin(fNumber / i) << std::endl;}std::cout << std::endl;for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << - fNumber / i << "): "<< std::asin(- fNumber / i) << std::endl;}std::cout << std::endl;const double dNumber = std::acos(-1);for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << dNumber / i << "): "<< std::asin(dNumber / i) << std::endl;}std::cout << std::endl;for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << - dNumber / i << "): "<< std::asin(- dNumber / i) << std::endl;}std::cout << std::endl;const long double ldNumber = std::acos(-1);std::cout << "typeid(long double).name(): " << typeid(long double).name() << std::endl;for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << ldNumber / i << "): "<< std::asin(ldNumber / i) << std::endl;}std::cout << std::endl;for (int i = 1; i <= 10; i += 1){std::cout << "std::asin(" << - ldNumber / i << "): "<< std::asin(- ldNumber / i) << std::endl;}std::cout << std::endl;return 0;
}
输出
typeid(float).name(): f
std::asin(3.14159): nan
std::asin(1.5708): nan
std::asin(1.0472): nan
std::asin(0.785398): 0.903339
std::asin(0.628319): 0.67939
std::asin(0.523599): 0.55107
std::asin(0.448799): 0.465421
std::asin(0.392699): 0.403565
std::asin(0.349066): 0.356574
std::asin(0.314159): 0.319571std::asin(-3.14159): nan
std::asin(-1.5708): nan
std::asin(-1.0472): nan
std::asin(-0.785398): -0.903339
std::asin(-0.628319): -0.67939
std::asin(-0.523599): -0.55107
std::asin(-0.448799): -0.465421
std::asin(-0.392699): -0.403565
std::asin(-0.349066): -0.356574
std::asin(-0.314159): -0.319571std::asin(3.14159): nan
std::asin(1.5708): nan
std::asin(1.0472): nan
std::asin(0.785398): 0.903339
std::asin(0.628319): 0.67939
std::asin(0.523599): 0.55107
std::asin(0.448799): 0.465421
std::asin(0.392699): 0.403565
std::asin(0.349066): 0.356574
std::asin(0.314159): 0.319571std::asin(-3.14159): nan
std::asin(-1.5708): nan
std::asin(-1.0472): nan
std::asin(-0.785398): -0.903339
std::asin(-0.628319): -0.67939
std::asin(-0.523599): -0.55107
std::asin(-0.448799): -0.465421
std::asin(-0.392699): -0.403565
std::asin(-0.349066): -0.356574
std::asin(-0.314159): -0.319571typeid(long double).name(): e
std::asin(3.14159): nan
std::asin(1.5708): nan
std::asin(1.0472): nan
std::asin(0.785398): 0.903339
std::asin(0.628319): 0.67939
std::asin(0.523599): 0.55107
std::asin(0.448799): 0.465421
std::asin(0.392699): 0.403565
std::asin(0.349066): 0.356574
std::asin(0.314159): 0.319571std::asin(-3.14159): nan
std::asin(-1.5708): nan
std::asin(-1.0472): nan
std::asin(-0.785398): -0.903339
std::asin(-0.628319): -0.67939
std::asin(-0.523599): -0.55107
std::asin(-0.448799): -0.465421
std::asin(-0.392699): -0.403565
std::asin(-0.349066): -0.356574
std::asin(-0.314159): -0.319571