fourier transform problem

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Alok Verma
Alok Verma 2011-9-8
评论： Leyla Ibrahimli 2020-11-21
Hi, i am trying make my own matlab program for fourier transform, whose result should be same as inbuilt library function fourier(f).
my program is:
function [fw]=myfourier(fx) syms x w; w=1; fw=int(fx*exp(-i*w*x),x,-pi,pi); and answer came are:
-pi*i for the myfourier(sin(x))
but by the library function:fourier(sin(x)) i got:
-pi*i(dirac(w - 1) - dirac(w + 1))*
and other answers are also different for different functions.
please help me for this program.
thanxs
  2 个评论
Alok Verma
Alok Verma 2011-9-9
Hi walter,
I have sending my function again:
function [fw]=myfourier(fx)
syms x w;
w=1;
fw=int(fx*exp(-i*w*x),x,-pi,pi);
in this function i got the answer '-pi*i'
but the answer of inbuit function is:
-pi*i(dirac(w - 1) - dirac(w + 1))
if possible help me.
i m not able to get the correct answer as given by library function. may be the problem of 'w'(omega) or aomthing problem of discontinuity of function.
i hope u now understand the problem.
Leyla Ibrahimli
Leyla Ibrahimli 2020-11-21
I also experience the same problem. The inverse fourier works with formula, because you dont have diracs there. I also tried (rewrite, f, dirac) but dirac is not a valid command in rewrite. So, if anyone solved the issue, it would be very nice to see the code thanks!

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回答（1 个）

Walter Roberson
Walter Roberson 2011-9-8
function [F(v)]=myfourier3(f(u))
is not legal syntax in MATLAB.
Please post your actual code.
  2 个评论
Alok Verma
Alok Verma 2011-9-9
Hi walter,
I have sending my function again:
function [fw]=myfourier(fx)
syms x w;
w=1;
fw=int(fx*exp(-i*w*x),x,-pi,pi);
in this function i got the answer '-pi*i'
but the answer of inbuit function is:
-pi*i(dirac(w - 1) - dirac(w + 1))
if possible help me.
i m not able to get the correct answer as given by library function. may be the problem of 'w'(omega) or aomthing problem of discontinuity of function.
i hope u now understand the problem.
Walter Roberson
Walter Roberson 2011-9-9
fourier involves integration from -infinity to +infinity, not -pi to +pi

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