Hi,
here is the command I typed.
a = Fourier[{{ConstantArray[1, {4, 1}]}, {ConstantArray[ 0, {12, 1}]}, {ConstantArray[1, {4, 1}]}}]
and get this error
Fourier::fftl: Argument {{{{1},{1},{1},{1}}},{{{0},{0},{0},{0},{0},{0},{0},{0},{0},{0},{0},{0}}},{{{1},{1},{1},{1}}}} is not a non-empty list or rectangular array of numeric quantities.
is there anyway out of this? The documentation does not give a clue.
What are you actually trying to compute the Fourier transform of? The argument of Fourier must be a rectangular array (a matrix) or a list of numeric quantities. The argument that you supplied to Fourier is neither of these. Do you want your argument to be a simple list of 1s and 0s? If that is the case then you must Flatten the argument as in
Fourier[Flatten[{{ConstantArray[1, {4, 1}]}, {ConstantArray[0, {12, 1}]}, {ConstantArray[1, {4, 1}]}}]]
The error messages are (often) quite informative, so read and reflect on them and look the examples over to get a sense of what may have gone wrong. In your case you would get a quick sense of what’s going wrong by examining the argument that you supplied to Fourier as in
MatrixForm[{{ConstantArray[1, {4, 1}]}, {ConstantArray[
0, {12, 1}]}, {ConstantArray[1, {4, 1}]}}]