Znn3bq.jpeg
²é¿´: 2499  |  »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

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
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)


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
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] ¿¼ÑÐÇóµ÷¼Á +4 ö©??? 2026-04-08 4/200 2026-04-08 21:44 by ÍÁľ˶ʿÕÐÉú
[¿¼ÑÐ] 085404£¬285·ÖÇóµ÷¼Á +4 Þ±Þ±¿¼ÑÐ 2026-04-07 4/200 2026-04-08 14:32 by zhq0425
[¿¼ÑÐ] Çóµ÷¼Á£¬ÏÖÔÚ»¹ÄÜÌîµÄ +3 Éϰ¶Ð¡Ó¨¼ÓÓÍ 2026-04-08 3/150 2026-04-08 14:30 by zhq0425
[¿¼ÑÐ] Çó²ÄÁϵ÷¼Á£¬Ò»Ö¾Ô¸Ö£ÖÝ´óѧ289·Ö +21 ˶ÐǸ° 2026-04-03 21/1050 2026-04-08 11:55 by Öí»á·É
[¿¼ÑÐ] 336²ÄÁÏÓ뻯¹¤085600Çóµ÷¼Á +19 Ë®ÐǼÇinfp 2026-04-05 22/1100 2026-04-07 21:11 by yongzhesheng
[¿¼ÑÐ] 302·ÖÇóµ÷¼Á Ò»Ö¾Ô¸°²»Õ´óѧ085601 +12 zyxÉϰ¶£¡ 2026-04-04 12/600 2026-04-07 02:09 by BruceLiu320
[¿¼ÑÐ] ÉúÎïѧѧ˶Çóµ÷¼Á£º351·ÖÒ»Ö¾Ô¸ÄϾ©Ê¦·¶´óѧÉúÎïѧרҵ +6 ¡­¡«¡¢Íõ¡­¡« 2026-04-06 7/350 2026-04-06 18:54 by macy2011
[¿¼ÑÐ] 285Çóµ÷¼Á +5 mapmath 2026-04-06 6/300 2026-04-06 17:18 by À¶ÔÆË¼Óê
[¿¼ÑÐ] ²ÄÁÏר˶322 +11 ¹þ¹þ¹þºðºðºð¹þ 2026-04-05 11/550 2026-04-06 14:07 by lqwchd
[¿¼ÑÐ] ¹¤¿Æ370Çóµ÷¼Á +3 äçÐļ弦µ° 2026-04-05 3/150 2026-04-06 10:55 by ÕâÊÇÒ»¸öÎÞÁĵÄê
[¿¼ÑÐ] ²ÄÁÏר˶(0856) 339·ÖÇóµ÷¼Á +10 ¹þ¹þ¹þ¶ì¹þ¹þ¹þ 2026-04-04 10/500 2026-04-05 18:51 by À¶ÔÆË¼Óê
[¿¼ÑÐ] 313Çóµ÷¼Á +5 º£ÈÕº£ÈÕ 2026-04-04 5/250 2026-04-05 15:52 by jndximd
[¿¼ÑÐ] µ÷¼Á +3 ºÃºÃ¶ÁÊé¡£ 2026-04-02 3/150 2026-04-05 13:02 by arrow8852
[¿¼ÑÐ] Ò»Ö¾Ô¸±±¾©»¯¹¤´óѧ£¬³õÊԳɼ¨350Çóµ÷¼Á +9 ÑØ°¶?±´¿Ç 2026-04-04 14/700 2026-04-05 01:09 by ÑØ°¶?±´¿Ç
[¿¼ÑÐ] 290Çóµ÷¼Á +7 luoziheng 2026-04-04 7/350 2026-04-04 23:17 by lqwchd
[¿¼ÑÐ] ²ÄÁÏÓ뻯¹¤306·ÖÕÒµ÷¼Á +23 ²×º£ÇáÖÛe 2026-04-02 27/1350 2026-04-04 21:52 by laoshidan
[¿¼ÑÐ] Çóµ÷¼Á +3 ffyyu 2026-04-02 3/150 2026-04-04 19:03 by À¶ÔÆË¼Óê
[¿¼ÑÐ] ±¾9Ò»Ö¾Ô¸2 0854µÍ·Öר˶286Çóµ÷¼Á +9 âÖÖ111 2026-04-04 9/450 2026-04-04 11:01 by tangruihua
[¿¼ÑÐ] 285Çóµ÷¼Á +7 AZMK 2026-04-02 9/450 2026-04-03 11:12 by wanwan00
[¿¼ÑÐ] Çóµ÷¼Á +7 Aniyaio 2026-04-02 7/350 2026-04-02 16:42 by zzsw+
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û