Implement fftshift1.sci in Scilab

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);