²é¿´: 2467  |  »Ø¸´: 6

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
¡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

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

holmescn

½ð³æ (ÕýʽдÊÖ)


¡ï ¡ï
ÓàÔó³É(½ð±Ò+2): лл²ÎÓëÓ¦Öú£¡ 2011-03-07 21:38:09
ûÓùýFFTW£¬²»¹ýÕâÁ½ÐÐȷʵ±È½ÏÆæ¹Ö
CODE:
  /* ****************************************************
   * Generate a single sine wave cycle
   * ****************************************************/
  int i;
  for (i=0; i < n; ++i){
    creal(b1[i])=sin((double)i/(double)n*2.0*M_PI);
    cimag(b1[i])=0;
  }

crealºÍcimagÊÇÁ½¸öº¯Êý»¹ÊÇÁ½¸öºê°¡¡£Èç¹ûÊÇÁ½¸öº¯Êý£¬ÄÇÕâÀï¿Ï¶¨ÊÇÓÐÎÊÌâµÄ¡£Èç¹ûÊÇÁ½¸öºê£¬²»ÖªµÀ»áÕ¹¿ª³Éʲô¡£
6Â¥2011-03-04 09:46:57
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

magic7004

½ð³æ (Ö°Òµ×÷¼Ò)


¡ï ¡ï
ÓàÔó³É(½ð±Ò+2): лл²ÎÓëÓ¦Öú£¡ 2011-03-10 14:17:18
¿´ÆðÀ´¾ÍÊÇcrealºÍcimagµÄÎÊÌâ°É..
7Â¥2011-03-08 16:00:08
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
Ïà¹Ø°æ¿éÌø×ª ÎÒÒª¶©ÔÄÂ¥Ö÷ eamtbfs µÄÖ÷Ìâ¸üÐÂ
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] 294Çóµ÷¼Á²ÄÁÏÓ뻯¹¤×¨Ë¶ +13 ݤÎÉ­ÁÖ 2026-03-18 13/650 2026-03-19 19:41 by maocaozhuxi
[¿¼ÑÐ] 307Çóµ÷¼Á +8 ÀäóÏ123 2026-03-17 8/400 2026-03-19 19:38 by maocaozhuxi
[¿¼ÑÐ] Ò»Ö¾Ô¸Ìì½ò´óѧ»¯Ñ§¹¤ÒÕרҵ£¨081702£©315·ÖÇóµ÷¼Á +11 yangfz 2026-03-17 11/550 2026-03-19 15:06 by houyaoxu
[¿¼ÑÐ] Ò»Ö¾Ô¸ÎäÀí²ÄÁÏ305·ÖÇóµ÷¼Á +5 ÏëÉϰ¶µÄÀðÓã 2026-03-18 6/300 2026-03-18 17:53 by Î޼ʵIJÝÔ­
[¿¼ÑÐ] 085600²ÄÁÏÓ뻯¹¤ +5 °²È«Éϰ¶£¡ 2026-03-16 5/250 2026-03-18 15:33 by cmz0325
[¿¼ÑÐ] 085601ר˶£¬×Ü·Ö342Çóµ÷¼Á£¬µØÇø²»ÏÞ +5 share_joy 2026-03-16 5/250 2026-03-18 14:48 by haxia
[¿¼ÑÐ] ÉúÎïѧ071000 329·ÖÇóµ÷¼Á +3 ÎÒ°®ÉúÎïÉúÎﰮΠ2026-03-17 3/150 2026-03-18 10:12 by macy2011
[¿¼ÑÐ] »·¾³¹¤³Ìµ÷¼Á +8 ´ó¿Édigkids 2026-03-16 8/400 2026-03-18 09:36 by zhukairuo
[¿¼ÑÐ] 277µ÷¼Á +5 ×ÔÓɼå±ý¹û×Ó 2026-03-16 6/300 2026-03-17 19:26 by Àîleezz
[¿¼ÑÐ] 085601Çóµ÷¼Á +4 Du.11 2026-03-16 4/200 2026-03-17 17:08 by ruiyingmiao
[¿¼ÑÐ] ÓÐûÓеÀÌú/ÍÁľµÄÏëµ÷¼ÁÄÏÁÖ£¬¸ø×Ô¼ºÕÐʦµÜÖС« +3 TqlXswl 2026-03-16 7/350 2026-03-17 15:23 by TqlXswl
[¿¼ÑÐ] ¶«ÄÏ´óѧ364Çóµ÷¼Á +5 JasonYuiui 2026-03-15 5/250 2026-03-16 21:28 by ľ¹Ï¸à
[¿¼ÑÐ] 318Çóµ÷¼Á +3 Yanyali 2026-03-15 3/150 2026-03-16 16:41 by houyaoxu
[¿¼ÑÐ] ÇóÀÏʦÊÕÁôµ÷¼Á +4 jiang½ª66 2026-03-14 5/250 2026-03-15 20:11 by Winj1e
[¿¼ÑÐ] 0856ר˶279Çóµ÷¼Á +5 ¼ÓÓͼÓÓÍ£¡? 2026-03-15 5/250 2026-03-15 11:58 by 2020015
[¿¼ÑÐ] 080500£¬²ÄÁÏѧ˶302·ÖÇóµ÷¼ÁѧУ +4 ³õʶ¿ÉÀÖ 2026-03-14 5/250 2026-03-14 21:08 by peike
[¿¼ÑÐ] 289Çóµ÷¼Á +4 ÕâôÃû×ÖÕ¦Ñù 2026-03-14 6/300 2026-03-14 18:58 by userper
[¿¼ÑÐ] Öпƴó²ÄÁÏר˶319Çóµ÷¼Á +3 ÃÏöβÄÁÏ 2026-03-13 3/150 2026-03-14 18:10 by houyaoxu
[¿¼ÑÐ] £Û0860£Ý321·ÖÇóµ÷¼Á£¬abÇø½Ô¿É +4 ±¦¹óÈÈ 2026-03-13 4/200 2026-03-13 22:01 by ÐÇ¿ÕÐÇÔÂ
[¿¼ÑÐ] 304Çóµ÷¼Á +7 7712b 2026-03-13 7/350 2026-03-13 21:42 by peike
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û