cacos函数用法详解

cacos函数简介

• 头文件包含

#include <complex.h>

• 函数定义

double complex cacos(double complex  z );
float complex cacosf(float complex  z );
long double complex cacosl(long double complex  z );

• 编译链接选项

-lm

cacos函数常见使用错误

• 链接错误
  undefined reference to `cacos'
  解决办法：添加链接选项

-lm

• 编译错误
  warning: implicit declaration of function ‘cacos’ [-Wimplicit-function-declaration]
  解决办法：包含头文件

#include <complex.h>

cacos函数详细描述

这些函数计算z 的复弧余弦，如果y = cacos(z)，然后pz = ccos(y)。在区间[0,pi]中选择y的实部。
一个有：

   cacos(z) = \-i * clog(z + i * csqrt(1 \- z * z))

cacos函数使用举例

/* Link with "\-lm" */

#include <complex.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>

int
main(int argc, char *argv[])
{
   double complex z, c, f;
   double complex i = I;

   if (argc != 3) {
       fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
       exit(EXIT_FAILURE);
   }

   z = atof(argv[1]) + atof(argv[2]) * I;

   c = cacos(z);

   printf("cacos() = %6.3f %6.3f*i\en", creal(c), cimag(c));

   f = \-i * clog(z + i * csqrt(1 \- z * z));

   printf("formula = %6.3f %6.3f*i\en", creal(f), cimag(f));

   exit(EXIT_SUCCESS);
}