如果直接gcc編譯，會(huì)出現(xiàn)未定義的情況：

/tmp/ccbS6FZx.o: In function `main':

fft.c:(.text+0x71): undefined reference to `sin'

fft.c:(.text+0x9f): undefined reference to `sin'

fft.c:(.text+0x25e): undefined reference to `pow'

fft.c:(.text+0x2d5): undefined reference to `pow'

fft.c:(.text+0x45e): undefined reference to `pow'

fft.c:(.text+0x548): undefined reference to `sqrt'

/tmp/ccbS6FZx.o: In function `Wn_i':

fft.c:(.text+0x64d): undefined reference to `cos'

fft.c:(.text+0x674): undefined reference to `sin'

collect2: error: ld returned 1 exit status

是因?yàn)槿鄙僬{(diào)用，具體需要添加-lm進(jìn)行編譯

gcc a.c -o a -lm

 其中a.c為源代碼，a為編譯后輸出結(jié)果， -lm為gcc選項(xiàng)

在編譯即可。