diff options
| -rw-r--r-- | macros/fftshift1.sci | 111 |
1 files changed, 80 insertions, 31 deletions
diff --git a/macros/fftshift1.sci b/macros/fftshift1.sci index cdff99a..db22891 100644 --- a/macros/fftshift1.sci +++ b/macros/fftshift1.sci @@ -1,32 +1,81 @@ -function y= fftshift1(X,DIM) -//Perform a shift of the vector X, for use with the 'fft1' and 'ifft1' functions, in order the move the frequency 0 to the center of the vector or matrix. -//Calling Sequence -// fftshift1 (X) -// fftshift1 (X, DIM) -//Parameters -//X:It is a vector of N elements corresponding to time samples -//DIM: The optional DIM argument can be used to limit the dimension along which the permutation occurs -//Description -//This is an Octave function. -//Perform a shift of the vector X, for use with the 'fft1' and 'ifft1' functions, in order the move the frequency 0 to the center of the vector or matrix. -// -//If X is a vector of N elements corresponding to N time samples spaced by dt, then 'fftshift1 (fft1 (X))' corresponds to frequencies -// -//f = [ -(ceil((N-1)/2):-1:1)*df 0 (1:floor((N-1)/2))*df ] -// -//where df = 1 / dt. -// -//If X is a matrix, the same holds for rows and columns. If X is an array, then the same holds along each dimension. -// -//The optional DIM argument can be used to limit the dimension along which the permutation occurs. - rhs= argn(2); - if(rhs <1 | rhs >2) - error('Wrong number of Input arguments'); - end - select(rhs) - case 1 then - y=callOctave("fftshift",X); - case 2 then - y=callOctave("fftshift",X,DIM); - end +function y = fftshift1(x, dim) +//Performs a shift of the vector x, for use with the fft1 and ifft1 functions, in order to move the frequency 0 to the center of the vector or matrix. +//Calling Sequence: +// fftshift1(x) +// fftshift1(x, dim) +//Parameters: +//x- It is a vector of N elements corresponding to time samples +//dim- The optional DIM argument can be used to limit the dimension along which the permutation occurs +//Examples: +//x = [0:6] +//fftshift1(x) +//ans = +//4 5 6 0 1 2 3 + + funcprot(0); + rhs = argn(2); + if (rhs < 1 | rhs > 2) then + error ("fftshift1: wrong number of arguments"); + end + + if (~or(type(x) == [1 5 8 10 4 6])) + error ("fftshitft1: arg1 (x) must be a vector or matrix"); + end + + if (rhs == 1) then + dim = 1:max(size(size(x))); + else + if (~(isscalar(dim) & dim > 0 & dim == fix(dim))) then + error ("fftshift1: arg2 (dim) must be a positive integer"); + end + end + + for d = dim + sz = size(x); + sz2 = ceil(sz(d) / 2); + dim_idx = [sz2+1:sz(d), 1:sz2]; + if (d == 1) then + x = x(dim_idx, :); + elseif ( d == max(size(size(x))) ) then + x = x(:, dim_idx); + else + idx = repmat({':'}, 1, max(size(size(x)))); + idx(d) = {dim_idx}; + x = x(idx{:}); + end + end + y = x; + endfunction + +//input validation: +//assert_checkerror("fftshift1()", "fftshift1: wrong number of arguments"); +//assert_checkerror("fftshift1(1, 2, 3)", "Wrong number of input arguments."); +//assert_checkerror("fftshift1(0:2, -1)", "fftshift1: arg2 (dim) must be a positive integer"); +//assert_checkerror("fftshift1(0:2, 0:3)", "fftshift1: arg2 (dim) must be a positive integer"); + +//test mx1 input: +//x = [0:7]; +//y = fftshift1 (x); +//assert_checkequal (y, [4 5 6 7 0 1 2 3]); +//assert_checkequal (fftshift1(y), x); + +//test 1xm input: +//x = [0:7]'; +//y = fftshift1(x); +//assert_checkequal(y, [4;5;6;7;0;1;2;3]); +//assert_checkequal(fftshift1(y), x); + +//test mxn input: +//x = [0:3]; +//x = [x;2*x;3*x+1;4*x+1]; +//y = fftshift1(x); +//assert_checkequal(y, [[7 10 1 4];[9 13 1 5];[2 3 0 1];[4 6 0 2]]); +//assert_checkequal(fftshift1(y), x); + +//test dim is provided: +//x = [0:3]; +//x = [x;2*x;3*x+1;4*x+1]; +//y = fftshift1(x, 1); +//assert_checkequal(y, [[1 4 7 10];[1 5 9 13];[0 1 2 3];[0 2 4 6]]); +//assert_checkequal(fftshift1(y, 1), x); |