Znn3bq.jpeg
²é¿´: 2506  |  »Ø¸´: 6
µ±Ç°Ö»ÏÔʾÂú×ãÖ¸¶¨Ìõ¼þµÄ»ØÌû£¬µã»÷ÕâÀï²é¿´±¾»°ÌâµÄËùÓлØÌû

eamtbfs

Í­³æ (СÓÐÃûÆø)


[½»Á÷] ¡¾ÇóÖú¡¿°ïæ¿´¿´ÄÄ´íÁËerror: invalid lvalue in assignment

ÎÒ×î½üÓõ½FFTW£¬¾ÍÍøÉÏÕÒÁ˸ö¼òµ¥Àý×ÓÀ´Ñ§Ï°ÁËÏ¡£µ«Õâ¸ö¼òµ¥Àý×Ó±àÒë³ö´í£¬²»ÖªµÀÔõô»ØÊ¡£ÎÒÍøÉϲéÁ˲飬Ҳû¸ãÇåÊÇFFTWÓï¾äµÄÎÊÌ⣬»¹ÊÇgcc±àÒëÆ÷µÄÎÊÌâ¡£Çë¸ßÊÖ°ïæ¿´¿´°¡£¡

´íÎóÐÅÏ¢ÈçÏ£º
$gcc34 FFTW_example.c -lfftw3 -lm
FFTW_example.c: In function `main':
FFTW_example.c:35: error: invalid lvalue in assignment
FFTW_example.c:36: error: invalid lvalue in assignment

ÓÃgcc4.3Ò²ÊÇÒ»Ñù³ö´í¡£

Õâ¸öFFTWµÄ¼òµ¥Àý×Ó³ÌÐòµÄÍøÖ·ÔÚÕâÀïhttp://www.elisanet.fi/mnentwig/webroot/FFTW_example/index.html

³ÌÐò±È½ÏС¾ÍÌùÔÚÏÂÃæ¡£ÊÇcreal ºÍcimagÄÇÁ½Ðгö´íÁË
/* ****************************************************
* FFTW example
* Markus Nentwig, 2007
* This program is in the public domain
* ****************************************************/
#include
#include
#include
#include
#include

int main(void){
  /* ****************************************************
   * Allocate memory
   * ****************************************************/
  int n=128;
  fftw_complex* b1=fftw_malloc(sizeof(fftw_complex)*n);
  fftw_complex* b2=fftw_malloc(sizeof(fftw_complex)*n);

  /* ****************************************************
   * Create forward FFT plan from b1 into b2
   * ****************************************************/
  fftw_plan p1=fftw_plan_dft_1d(n, b1, b2, FFTW_FORWARD, FFTW_ESTIMATE);

  /* ****************************************************
   * Create reverse FFT plan from b2 into b1
   * ****************************************************/
  fftw_plan p2=fftw_plan_dft_1d(n, b2, b1, FFTW_BACKWARD, FFTW_ESTIMATE);

  /* ****************************************************
   * Generate a single sine wave cycle
   * ****************************************************/
  int i;
  for (i=0; i < n; ++i){
    creal(b1)=sin((double)i/(double)n*2.0*M_PI);
    cimag(b1)=0;
  }
  
  /* ****************************************************
   * Execute FFT from b1 into b2
   * ****************************************************/
  fftw_execute(p1);

  /* ****************************************************
   * Dump the "spectrum".
   * Result:
   * First bin ("DC  term" is zero
   * * i*n/2 in 2nd bin
   * * -i*n/2 in last bin
   * * all other bins are zero
   * ****************************************************/
  for (i=0; i < n; ++i){
    printf("%1.7f\t%1.7f\n", creal(b2), cimag(b2));
  };

  /* ****************************************************
   * IFFT back into b1
   * ****************************************************/
  fftw_execute(p2);
  printf("\n";

  /* ****************************************************
   * Result: Original waveform scaled by n
   * ****************************************************/
  for (i=0; i < n; ++i){
    printf("%1.7f\t%1.7f\n", creal(b1), cimag(b1));
  };

  /* ****************************************************
   * Clean up
   * ****************************************************/
  fftw_destroy_plan(p1);
  fftw_destroy_plan(p2);

  fftw_free(b1);
  fftw_free(b2);
  return 0;
}
»Ø¸´´ËÂ¥

» ²ÂÄãϲ»¶

» ±¾Ö÷ÌâÏà¹Ø¼ÛÖµÌùÍÆ¼ö£¬¶ÔÄúͬÑùÓаïÖú:

» ÇÀ½ð±ÒÀ²£¡»ØÌû¾Í¿ÉÒԵõ½:

²é¿´È«²¿É¢½ðÌù

ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

lucktroy

½û³æ (СÓÐÃûÆø)

¡ï ¡ï ¡ï
ÓàÔó³É(½ð±Ò+3): лл²ÎÓëÓ¦Öú£¡ 2011-02-28 20:09:22
±¾ÌûÄÚÈݱ»ÆÁ±Î

5Â¥2011-02-28 19:25:46
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
²é¿´È«²¿ 7 ¸ö»Ø´ð
¡ï ¡ï ¡ï
eamtbfs(½ð±Ò+1): лл²ÎÓë 2011-02-25 06:01:14
ÓàÔó³É(½ð±Ò+3): лл²ÎÓëÓ¦Öú£¡ 2011-02-27 15:06:29
³­¶¼Ã»³­¶Ô¿©
CODE:
    creal(b1[i])=sin((double)i/(double)n*2.0*M_PI);
    cimag(b1[i])=0;

CODE:
printf("%1.7f\t%1.7f\n", creal(b1[i]), cimag(b1[i]));

2Â¥2011-02-24 19:31:36
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

eamtbfs

Í­³æ (СÓÐÃûÆø)


zzzzz

[ Last edited by eamtbfs on 2011-2-25 at 06:06 ]
3Â¥2011-02-25 06:04:26
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

eamtbfs

Í­³æ (СÓÐÃûÆø)


ÒýÓûØÌû:
Originally posted by yalefield at 2011-02-24 19:31:36:
³­¶¼Ã»³­¶Ô¿©
CODE:
    creal(b1[i])=sin((double)i/(double)n*2.0*M_PI);
    cimag(b1[i])=0;

CODE:
printf("%1.7f\t%1.7f\n", creal(b1[i]), cimag(b1[i]));


ÎÒ´ÓÍøÒ³ÉÏÌû¹ýÀ´µÄ£¬²»ÖªÔõôÌù¹ýÀ´¾Í±äÁË¡£²»¹ýÎÒ±àÒëµÄʱºòÊÇÓõÄÍøÉÏÏÂÔØµÄ³ÌÐò£¬ÎÒ×Ðϸ¿´ÁË£¬ÎÒ±àÒëµÄ³ÌÐòÓ﷨ûÓÐÕâÑùµÄ´í£¬µ«¾ÍÊÇgcc±¨¸æerror: invalid lvalue in assignment

Çë°ïæ±àÒëÏ£¬¿´¿´ÎÊÌâ³öÔÚÄÄ¡£¶àл¶àл£¡
4Â¥2011-02-25 06:05:21
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] Çóµ÷¼Á +7 MAXâê㯠2026-04-09 8/400 2026-04-09 21:37 by ½¯ð©Óí
[¿¼ÑÐ] 286Çóµ÷¼Á +6 ²Ýľ²»ÑÔ 2026-04-04 6/300 2026-04-09 21:06 by 286640313
[¿¼ÑÐ] 0854µ÷¼Á +10 ³¤¹­°Á 2026-04-09 11/550 2026-04-09 19:03 by ̽123
[¿¼ÑÐ] 296Çóµ÷¼Á +5 Íô£¡£¿£¡ 2026-04-09 5/250 2026-04-09 17:47 by ÄûÃʲ»Ëázy
[¿¼ÑÐ] 368»¯Ñ§Çóµ÷¼Á +13 wwwwabcde 2026-04-07 14/700 2026-04-09 14:47 by heaven_jay
[¿¼ÑÐ] 296Çóµ÷¼Á +3 Íô£¡£¿£¡ 2026-04-08 3/150 2026-04-08 22:00 by zhouyuwinner
[¿¼ÑÐ] Çóµ÷¼Á +9 ÔÂ@163.com 2026-04-07 11/550 2026-04-08 14:48 by qlm5820
[¿¼ÑÐ] 285Çóµ÷¼Á +7 ¶ñ·¨´ó¶þµÄÆøÎ¶ß 2026-04-05 10/500 2026-04-08 14:34 by zhq0425
[¿¼ÑÐ] ²ÄÁÏר˶ µ÷¼Á +17 CXN123456 2026-04-03 17/850 2026-04-08 11:10 by lijunpoly
[¿¼ÑÐ] 338Çóµ÷¼Á +5 СÖíºìÉ« 678 2026-04-06 6/300 2026-04-07 21:18 by ÇÇßÕßÕßÕ
[¿¼²©] ²©Ê¿ÉêÇë +3 IQwQl 2026-04-05 3/150 2026-04-07 20:31 by greychen00
[¿¼ÑÐ] ²ÄÁϵ÷¼Á +11 Ò»ÑùYWY 2026-04-07 11/550 2026-04-07 15:13 by shdgaomin
[¿¼ÑÐ] »úеר˶274Çóµ÷¼Á£¬²»ÌôרҵѧУ +6 ·º·º2333 2026-04-05 8/400 2026-04-06 18:06 by ·º·º2333
[¿¼ÑÐ] 328·Öµ÷¼Á +6 ÃÅmen 2026-04-04 6/300 2026-04-05 13:40 by imissbao
[¿¼ÑÐ] 358Çóµ÷¼Á +7 Çïgk 2026-04-04 7/350 2026-04-05 13:29 by huangmoli
[¿¼ÑÐ] 353Çóµ÷¼Á +10 MayUxw1 2026-04-03 10/500 2026-04-05 09:23 by Î޼ʵIJÝÔ­
[¿¼ÑÐ] 311·Ö 22408 Çóµ÷¼Á +3 bing_bot 2026-04-03 3/150 2026-04-05 00:43 by chongya
[¿¼ÑÐ] Çóµ÷¼Á +3 ũҵ¹¤³ÌÓëÐÅÏ¢¼ 2026-04-04 3/150 2026-04-04 12:19 by Éá¶øºóµÃ
[¿¼ÑÐ] 278Çóµ÷¼Á +6 Yy7400 2026-04-03 6/300 2026-04-04 09:53 by zhangdingwa
[¿¼ÑÐ] 305Çóµ÷¼Á +3 77Qi 2026-04-03 3/150 2026-04-03 23:01 by qzxyhcsy
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û