[求助]ifft的使用问题 - MATLAB爱好者论坛-LabFans.com

jww100 · 2008-09-14, 03:24

各位大侠，我是个菜鸟，现有一个频域转时域的ifft问题一直搞不懂，恳请指教

H11 =
(-3/4*w^4+1095/2*i*w^3+129500*w^2-14950000*i*w-747500000)/(3*w^6-2865*i*w^5-956750*w^4+158800000*i*w^3+14127500000*w^2-742500000000*i*w-24750000000000)

subs(H11,w,-pi

i/50

i)

ans =
1.0e-004 *
Columns 1 through 9
0.3023 + 0.0095i 0.3023 + 0.0093i 0.3023 + 0.0091i 0.3023 + 0.0089i 0.3023 + 0.0088i 0.3023 + 0.0086i 0.3022 + 0.0084i 0.3022 + 0.0082i 0.3022 + 0.0080i
Columns 10 through 18
0.3022 + 0.0078i 0.3022 + 0.0076i 0.3022 + 0.0074i 0.3022 + 0.0072i 0.3022 + 0.0070i 0.3022 + 0.0068i 0.3022 + 0.0067i 0.3022 + 0.0065i 0.3021 + 0.0063i
Columns 19 through 27
0.3021 + 0.0061i 0.3021 + 0.0059i 0.3021 + 0.0057i 0.3021 + 0.0055i 0.3021 + 0.0053i 0.3021 + 0.0051i 0.3021 + 0.0049i 0.3021 + 0.0047i 0.3021 + 0.0046i
Columns 28 through 36
0.3021 + 0.0044i 0.3021 + 0.0042i 0.3021 + 0.0040i 0.3021 + 0.0038i 0.3021 + 0.0036i 0.3021 + 0.0034i 0.3021 + 0.0032i 0.3020 + 0.0030i 0.3020 + 0.0028i
Columns 37 through 45
0.3020 + 0.0027i 0.3020 + 0.0025i 0.3020 + 0.0023i 0.3020 + 0.0021i 0.3020 + 0.0019i 0.3020 + 0.0017i 0.3020 + 0.0015i 0.3020 + 0.0013i 0.3020 + 0.0011i
Columns 46 through 54
0.3020 + 0.0009i 0.3020 + 0.0008i 0.3020 + 0.0006i 0.3020 + 0.0004i 0.3020 + 0.0002i 0.3020 0.3020 - 0.0002i 0.3020 - 0.0004i 0.3020 - 0.0006i
Columns 55 through 63
0.3020 - 0.0008i 0.3020 - 0.0009i 0.3020 - 0.0011i 0.3020 - 0.0013i 0.3020 - 0.0015i 0.3020 - 0.0017i 0.3020 - 0.0019i 0.3020 - 0.0021i 0.3020 - 0.0023i
Columns 64 through 72
0.3020 - 0.0025i 0.3020 - 0.0027i 0.3020 - 0.0028i 0.3020 - 0.0030i 0.3021 - 0.0032i 0.3021 - 0.0034i 0.3021 - 0.0036i 0.3021 - 0.0038i 0.3021 - 0.0040i
Columns 73 through 81
0.3021 - 0.0042i 0.3021 - 0.0044i 0.3021 - 0.0046i 0.3021 - 0.0047i 0.3021 - 0.0049i 0.3021 - 0.0051i 0.3021 - 0.0053i 0.3021 - 0.0055i 0.3021 - 0.0057i
Columns 82 through 90
0.3021 - 0.0059i 0.3021 - 0.0061i 0.3021 - 0.0063i 0.3022 - 0.0065i 0.3022 - 0.0067i 0.3022 - 0.0068i 0.3022 - 0.0070i 0.3022 - 0.0072i 0.3022 - 0.0074i
Columns 91 through 99
0.3022 - 0.0076i 0.3022 - 0.0078i 0.3022 - 0.0080i 0.3022 - 0.0082i 0.3022 - 0.0084i 0.3023 - 0.0086i 0.3023 - 0.0088i 0.3023 - 0.0089i 0.3023 - 0.0091i
Columns 100 through 101
0.3023 - 0.0093i 0.3023 - 0.0095i

>> h11=ifft(H11)
??? Function 'ifft' is not defined for values of class 'sym'.

我想问问我这用ifft到底出了什么问题
有什么更好的方法吗？
感谢万分！

2008-09-14, 03:24	#1
jww100 初级会员注册日期: 2008-09-05 年龄: 43 帖子: 1 声望力: 0	[求助]ifft的使用问题各位大侠，我是个菜鸟，现有一个频域转时域的ifft问题一直搞不懂，恳请指教 H11 = (-3/4w^4+1095/2iw^3+129500w^2-14950000iw-747500000)/(3w^6-2865iw^5-956750w^4+158800000iw^3+14127500000w^2-742500000000iw-24750000000000) subs(H11,w,-pii/50i) ans = 1.0e-004 Columns 1 through 9 0.3023 + 0.0095i 0.3023 + 0.0093i 0.3023 + 0.0091i 0.3023 + 0.0089i 0.3023 + 0.0088i 0.3023 + 0.0086i 0.3022 + 0.0084i 0.3022 + 0.0082i 0.3022 + 0.0080i Columns 10 through 18 0.3022 + 0.0078i 0.3022 + 0.0076i 0.3022 + 0.0074i 0.3022 + 0.0072i 0.3022 + 0.0070i 0.3022 + 0.0068i 0.3022 + 0.0067i 0.3022 + 0.0065i 0.3021 + 0.0063i Columns 19 through 27 0.3021 + 0.0061i 0.3021 + 0.0059i 0.3021 + 0.0057i 0.3021 + 0.0055i 0.3021 + 0.0053i 0.3021 + 0.0051i 0.3021 + 0.0049i 0.3021 + 0.0047i 0.3021 + 0.0046i Columns 28 through 36 0.3021 + 0.0044i 0.3021 + 0.0042i 0.3021 + 0.0040i 0.3021 + 0.0038i 0.3021 + 0.0036i 0.3021 + 0.0034i 0.3021 + 0.0032i 0.3020 + 0.0030i 0.3020 + 0.0028i Columns 37 through 45 0.3020 + 0.0027i 0.3020 + 0.0025i 0.3020 + 0.0023i 0.3020 + 0.0021i 0.3020 + 0.0019i 0.3020 + 0.0017i 0.3020 + 0.0015i 0.3020 + 0.0013i 0.3020 + 0.0011i Columns 46 through 54 0.3020 + 0.0009i 0.3020 + 0.0008i 0.3020 + 0.0006i 0.3020 + 0.0004i 0.3020 + 0.0002i 0.3020 0.3020 - 0.0002i 0.3020 - 0.0004i 0.3020 - 0.0006i Columns 55 through 63 0.3020 - 0.0008i 0.3020 - 0.0009i 0.3020 - 0.0011i 0.3020 - 0.0013i 0.3020 - 0.0015i 0.3020 - 0.0017i 0.3020 - 0.0019i 0.3020 - 0.0021i 0.3020 - 0.0023i Columns 64 through 72 0.3020 - 0.0025i 0.3020 - 0.0027i 0.3020 - 0.0028i 0.3020 - 0.0030i 0.3021 - 0.0032i 0.3021 - 0.0034i 0.3021 - 0.0036i 0.3021 - 0.0038i 0.3021 - 0.0040i Columns 73 through 81 0.3021 - 0.0042i 0.3021 - 0.0044i 0.3021 - 0.0046i 0.3021 - 0.0047i 0.3021 - 0.0049i 0.3021 - 0.0051i 0.3021 - 0.0053i 0.3021 - 0.0055i 0.3021 - 0.0057i Columns 82 through 90 0.3021 - 0.0059i 0.3021 - 0.0061i 0.3021 - 0.0063i 0.3022 - 0.0065i 0.3022 - 0.0067i 0.3022 - 0.0068i 0.3022 - 0.0070i 0.3022 - 0.0072i 0.3022 - 0.0074i Columns 91 through 99 0.3022 - 0.0076i 0.3022 - 0.0078i 0.3022 - 0.0080i 0.3022 - 0.0082i 0.3022 - 0.0084i 0.3023 - 0.0086i 0.3023 - 0.0088i 0.3023 - 0.0089i 0.3023 - 0.0091i Columns 100 through 101 0.3023 - 0.0093i 0.3023 - 0.0095i >> h11=ifft(H11) ??? Function 'ifft' is not defined for values of class 'sym'. 我想问问我这用ifft到底出了什么问题有什么更好的方法吗？感谢万分！