catan函数用法详解

catan函数简介

• 头文件包含

#include <complex.h>

• 函数定义

double complex catan(double complex  z );
float complex catanf(float complex  z );
long double complex catanl(long double complex  z );

• 编译链接选项

-lm

catan函数常见使用错误

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

-lm

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

#include <complex.h>

catan函数详细描述

这些函数计算z 的复反正切，如果y = catan(z)，然后z = ctan(y)。y的实部选在区间[\-pi/2,pi/2]内。
一个有：

   catan(z) = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i)

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

   f = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i);
   printf("formula = %6.3f %6.3f*i\en", creal(f2), cimag(f2));

   exit(EXIT_SUCCESS);
}