循环遍历结构数组时出错

Question

我在C中为Parallax Propeller编写了一个FFT，它不会编译。我认为这是一个问题，我如何使用结构（我是C的新手，将所有这些都从Clojure中翻译出来），但我甚至无法隔离问题来解决问题。删除代码的某些部分允许它编译，但我无法做出正面或反面。我已经在结构和数组上查找了所有内容，现在我需要更多的帮助！谢谢！

编译器错误在最后发布。

#include "simpletools.h"
#include "math.h"
#include "complex.h"
void fft();
int pow2(int exp);  // Added to fix one of two problems

float complex ibi[256];


int main(void)
{
 for(int i = 0; i < 256; i++)
  {
  ibi[i] = 1.0 + 1.0 * I;
  } 
}

void fft()
{
  int log2n = 8;
  int length = 256;
  float pi = 3.1415;  
  for(int i = 0; i< log2n; i++)
  {
    int n1 = pow2(i);
    int n2 = pow2(i + 1);
    for (int j = 0; j< n1; j++)
    {
      for (int k = j; k < length; k= k + n2)
      {
      int k2 = k + n1;

      float complex dw, nw, df, nf;
      float da = pi * j / n1;
      float na = pi * (n1 + j) / n1;

      dw = cos(da) + -sin(da) * I;
      nw = cos(na) + -sin(na) * I;      

      df = ibi[k2] * dw;
      nf = ibi[k2] * nw;

      ibi[k2] = ibi[k] + nf;
      ibi[k]  = ibi[k] + df;

   }
   }
 }
}

int pow2(int exp)
{
  int answer = 2;
  for(int i = 0; i< exp; i++)
    {
    answer = answer * 2;
    }
  return answer;
}

编译时出错：

propeller-elf-gcc -v GCC 4.6.1 (propellergcc_v1_0_0_2261)
propeller-elf-gcc -I . -L . \
    -I /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Utility/libsimpletools \
    -L /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Utility/libsimpletools/cmm/ \
    -I /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Text Devices/libsimpletext \
    -L /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Text Devices/libsimpletext/cmm/ \
    -I /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Protocol/libsimplei2c \
    -L /home/steffan/Documents/SimpleIDE/Learn/Simple Libraries/Protocol/libsimplei2c/cmm/ \
    -o cmm/ECG2.elf -Os -mcmm -Wall -m32bit-doubles -fno-exceptions -std=c99 \
    ECG2.c -lsimpletools -lsimpletext -lsimplei2c -lsimpletools -lsimpletext \
    -lsimpletools
/tmp/ccdKeRAK.o: In function `.L9':
(.text+0x97): undefined reference to `_cexpf'
/tmp/ccdKeRAK.o: In function `.L9':
(.text+0xba): undefined reference to `_cexpf'
collect2: ld returned 1 exit status
Done. Build Failed!

Check source for bad function call or global variable name `_cexpf'
/tmp/ccdKeRAK.o: In function `.L9':
(.text+0xba):