- #1
elegysix
- 406
- 15
Thanks for any help! I'm trying to understand the coefficients of a 2d DFT.
say we've got this matrix, f(a,b)
[itex]
\left( \begin{array}{ccc}
9 & 1 & 9 \\
9 & 1 & 9 \\
9 & 1 & 9 \end{array} \right)
[/itex]
I used wolfram alpha's function, Fourier{f(a,b)}
and the transform comes back as
[itex]
\left( \begin{array}{ccc}
19 & 4-6.93i & 4+6.93i \\
0 & 0 & 0 \\
0 & 0 & 0 \end{array} \right)
[/itex]the characteristic polynomial is [itex] 19x^{2} - x^{3} [/itex]I know the coeffecient at (0,0) is an average of something, but what?
what are the other two coefficients in the top row?
If I do a matrix with a frequency in both directions, I get coefficients in the first column as well. What do they represent?
Is there enough information here to determine a function z(x,y) that approximates f(a,b)? (like a sum of sines and cosines)
three eigenvectors are given as well, if needed
thanks for your help!
say we've got this matrix, f(a,b)
[itex]
\left( \begin{array}{ccc}
9 & 1 & 9 \\
9 & 1 & 9 \\
9 & 1 & 9 \end{array} \right)
[/itex]
I used wolfram alpha's function, Fourier{f(a,b)}
and the transform comes back as
[itex]
\left( \begin{array}{ccc}
19 & 4-6.93i & 4+6.93i \\
0 & 0 & 0 \\
0 & 0 & 0 \end{array} \right)
[/itex]the characteristic polynomial is [itex] 19x^{2} - x^{3} [/itex]I know the coeffecient at (0,0) is an average of something, but what?
what are the other two coefficients in the top row?
If I do a matrix with a frequency in both directions, I get coefficients in the first column as well. What do they represent?
Is there enough information here to determine a function z(x,y) that approximates f(a,b)? (like a sum of sines and cosines)
three eigenvectors are given as well, if needed
thanks for your help!