i want to the fft for this bp but i have this error Error using fft Invalid data type. First argument must be double, single, int8, uint8, int16, uint16, int32, uint32, or log

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ahmad salahat 2023-1-19

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评论： Walter Roberson 2023-1-19

采纳的回答： Star Strider

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Answer 1

Star Strider 2023-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/1897160-i-want-to-the-fft-for-this-bp-but-i-have-this-error-error-using-fft-invalid-data-type-first-argumen#answer_1152210

Assuming that ‘bp’ does not contain any symbolic variables, perhaps this —

FTbp = fft(double(bp));

This also assigns it to a variable to make it easier to work with later.

.

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ahmad salahat 2023-1-19

编辑：Walter Roberson 2023-1-19

在 MATLAB Online 中打开

syms x n t g b m z d k v p c s q bp ss

n=1:3

n = 1×3

1 2 3

w=(2*pi)/0.1

w = 62.8319

x=heaviside(t)-((t-0.05).*heaviside(t-0.05))+((t-0.1).*heaviside(t-0.1));

a0=(1/0.1)*int(x,t,0,0.1)

a0 =

an=(2/0.1)*int(x*cos(n*w*t),t,0,0.1)

an =

bn=(2/0.1)*int(x*sin(n*w*t),t,0,0.1)

bn =

d=a0+an(1)*cos(w*t)+bn(1)*sin(w*t)

d =

z=a0+an(2)*cos(2*w*t)+bn(2)*sin(2*w*t)

z =

p=a0+an(3)*cos(3*w*t)+bn(3)*sin(3*w*t)

p =

m=a0+an(1)*cos(w*t)+an(2)*cos(2*w*t)+an(3)*cos(3*w*t)+bn(1)*sin(w*t)+bn(2)*sin(2*w*t)+bn(3)*sin(3*w*t)

m =

fplot(x,t)

hold on

fplot(t,m)

hold off

k=(x-d)^2

k =

v=(1/0.1)*int(k,t,0,0.1)

v =

fs=400

fs = 400

t=0:(1/fs):1

t = 1×401

0 0.0025 0.0050 0.0075 0.0100 0.0125 0.0150 0.0175 0.0200 0.0225 0.0250 0.0275 0.0300 0.0325 0.0350 0.0375 0.0400 0.0425 0.0450 0.0475 0.0500 0.0525 0.0550 0.0575 0.0600 0.0625 0.0650 0.0675 0.0700 0.0725

c=10*cos(2*pi*200*t)

c = 1×401

10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10 10 -10

plot(t,c)

s=c*p

s =

bpFilt = designfilt('bandpassfir','FilterOrder',1000, ...

'CutoffFrequency1',200,'CutoffFrequency2',300, ...

'SampleRate',1500);

fvtool(bpFilt)

This functionality is not available on remote platforms.

dataout=filter(bpFilt,s)

Walter Roberson 2023-1-19

在 MATLAB Online 中打开

Your s contains symbolic values such as

sin(60*pi*t)/(6*pi) - cos(60*pi*t)/(9*pi^2) + 79/8

filter() is not able to process symbolic variables.

You cannot get fft() of symbolic variables. fft() is something that only applies to numeric data. To get a fourier transform of symbolic values you need to use fourier

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