Transcript of FFT work in Scilab



                  Scilab-2.4  (July 12, 1998) 
                  Copyright (C) 1989-98 INRIA 
 
 
Startup execution:
  loading initial environment
 
-->horn_period_1 = loadwave('horn_period_1.wav');
Reading Wave file: Microsoft PCM format, 1 channel, 44100 samp/sec
        88200 byte/sec, 2 block align, 16 bits/samp, 1452 data bytes
Input file: using sample rate 44100
        size shorts, style signed (2's complement), 1 channel
 
-->plot2d(horn_period_1);
 
-->horn_spectrum_1_1 = fft(horn_period_1, -1);
 
-->xbasc();
 
-->plot2d(abs(horn_spectrum_1_1));
 
-->xbasc()
 
-->plot2d(abs(horn_spectrum_1_1(1:50)));
 
-->xbasc()                              
 
-->plot2d(abs(horn_spectrum_1_1(1:25)));
 
-->horn_spectrum_1_1(1:21)'
 ans  =
 
! - 1.839E-15              !
!   6.3315007 + 3.1397456i !
!   2.4078011 + 13.89031i  !
! - 14.391669 + 14.390421i !
! - 35.141659 +  .3307903i !
! - 30.637255 - 25.59816i  !
! - 12.564497 - 58.052689i !
!   48.828733 - 41.371947i !
!   46.606208 + 15.830319i !
!   9.7633612 + 32.971872i !
! - 19.910462 + 15.716832i !
! - 11.95423 - 6.0675731i  !
! - 1.1814681 - 8.7873691i !
!   3.9905353 - 4.9504942i !
!   4.4550595 +  .0266806i !
!   2.6291955 + 2.4229177i !
! -  .4063534 + 2.4452245i !
! - 1.7324988 + 1.0533957i !
! - 1.0191908 -  .6054199i !
! -  .0649969 -  .6021413i !
!    .2299578 -  .1274739i !
 
-->abs(horn_spectrum_1_1(1:21)')
 ans  =
 
!   0.        !
!   7.0672415 !
!   14.097454 !
!   20.352011 !
!   35.143216 !
!   39.923767 !
!   59.396812 !
!   63.999088 !
!   49.221313 !
!   34.387026 !
!   25.366224 !
!   13.405934 !
!   8.866438  !
!   6.3585978 !
!   4.4551394 !
!   3.57536   !
!   2.478759  !
!   2.0276081 !
!   1.1854464 !
!    .6056391 !
!    .2629262 !
 
-->arg(horn_spectrum_1_1(1:21)')
                              !--error     4 
undefined variable : arg                     
 
 
-->getf('fourier_demo.sci')
 
-->arg(horn_spectrum_1_1(1:21)')
 ans  =
 
! - 3.1415927 !
!    .4603564 !
!   1.399158  !
!   2.3562379 !
!   3.1321799 !
! - 2.445563  !
! - 1.7839414 !
! -  .7029169 !
!    .3274347 !
!   1.2829105 !
!   2.4733637 !
! - 2.6719098 !
! - 1.7044456 !
! -  .8923540 !
!    .0059888 !
!    .7445908 !
!   1.7354738 !
!   2.5952962 !
! - 2.6055817 !
! - 1.678323  !
! -  .5061661 !
 
-->plot_spectrum(horn_spectrum_1_1, 0, 44100);
 
-->xbasc()
 
-->plot_spectrum(horn_spectrum_1_1, 0, 44100);
 
-->xbasc()                                                        
 
-->plot_spectrum(mtlb_fftshift(horn_spectrum_1_1), -22050, 22050);

-->xbasc()
 
-->plot_spectrum(horn_spectrum_1_1(1:25), 0, 44100*25/size(horn_spectrum_1_1,2));
 
-->(arg(horn_spectrum_1_1(1:21)')/%pi+1)/2
 ans  =
 
!   0.        !
!    .573268  !
!    .7226829 !
!    .8750069 !
!    .9985019 !
!    .1107766 !
!    .2160769 !
!    .3881273 !
!    .5521129 !
!    .7041815 !
!    .8936481 !
!    .0747524 !
!    .2287291 !
!    .3579774 !
!    .5009531 !
!    .6185053 !
!    .7762092 !
!    .9130542 !
!    .0853088 !
!    .2328866 !
!    .4194412 !
 
-->

Michael J. O'Donnell
Last modified: Tue May 11 16:52:36 CDT 1999