How to do correctly DFT of the x,y data?

Question

Veronika 2017-1-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/318726-how-to-do-correctly-dft-of-the-x-y-data

评论： Veronika 2017-1-4

Dear all,

I have coordinates x_okoli,y_okoli and I would like to show output, but this error appears:

Undefined function 'fftgui' for input arguments of type 'double'.

Error in mesh_okoli (line 96) fftgui(m)

This is my code: x = x_okoli(1,1); y = y_okoli(1,1); z = x + i*y; A = abs(z); fi = angle(z); %fi2 = atan2(imag(z),real(z)) f = 50; omega = 2*pi*f; m = A*cos(omega*x+fi)+A*i*sin(omega*y+fi); figure(7) fftgui(m)

Thank you for your answers.

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Veronika 2017-1-2

Thank you.

Veronika 2017-1-2

编辑：Veronika 2017-1-2

在 MATLAB Online 中打开

mesh_okoli.m

For one coordinate value it works, but for all the coordinates it says this error:

Error using  * 
Inner matrix dimensions must agree.
Error in mesh_okoli (line 94)
m = A*cos(omega*x+fi)+A*i*sin(omega*y+fi);

This is my code:

for x = x_okoli(:,1);
    y = y_okoli(:,1);
z = x + i*y;
A = abs(z);
fi = angle(z);
%fi2 = atan2(imag(z),real(z))
f = 50;
omega = 2*pi*f;
m = A*cos(omega*x+fi)+A*i*sin(omega*y+fi);
figure(7)
fftgui(m)
end

x_okoli and y_okoli is my coordinates. I attach my code too. Can you help me and tell where is the mistake?

Thank you for your answer.

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Answer 1

Image Analyst 2017-1-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/318726-how-to-do-correctly-dft-of-the-x-y-data#answer_249183

在 MATLAB Online 中打开

Regarding

m = A*cos(omega*x+fi)+A*i*sin(omega*y+fi);

either look in the debugger (like most people) or add these lines before that line

whos A
whos i
whos omega
whos y
whos fi

First read this link and then, in the editor in MATLAB, type control a (to select all) and control i (to properly indent) then copy, then paste your answer back here.

Chances are, one of those is an array and you were expecting a scalar, so it's doing a matrix multiply instead of a scalar or element-by-element multiply.

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Veronika 2017-1-4

在 MATLAB Online 中打开

mesh_okoli.m

%%Mesh okolí
for x = x_okoli(:,1);
    y = y_okoli(:,1);
z = x + i*y;
A = abs(z);
fi = angle(z);
%fi2 = atan2(imag(z),real(z))
f = 50;
omega = 2*pi*f;
m = A*cos(omega*x+fi)+A*i*sin(omega*y+fi);
figure(7)
fftgui(m)
end