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// Returns input data in digit-reversed order
// Calling Sequence
//[y,i] = digitrevorder(x,r)
//y = digitrevorder(x,r)
// Parameters
//x: Vector of real or complex values
//r: radix / base
//y: input vector in digit reverse order
//i: indices
// Description
//This function returns the input data after reversing the digits of the indices and reordering the elements of the input array.
// Examples
//x = [%i,1,3,6*%i] ;
//r = 2 ;
//[y i]=digitrevorder(x, r)
//Output :
// i =
//
// 1. 3. 2. 4.
// y =
//
// i 3. 1. 6.i
function [y, i] = digitrevorder (x, r)
funcprot(0);
[nargout, nargin] = argn() ;
if (nargin > 2 | nargin <= 1)
error("digitrevorder : invalid number of inputs")
elseif (~ isvector (x))
error ("digitrevorder : X must be a vector");
elseif (~ (isscalar (r) & r == fix (r) & r >= 2 & r <= 36))
error ("digitrevorder : R must be an integer between 2 and 36");
else
tmp = log (length(x)) / log (r);
if (fix (tmp) ~= tmp)
error ("digitrevorder: X must have length equal to an integer power of radix");
end
end
old_ind = 0:length(x) - 1;
//new_ind = base2dec(mtlb_fliplr(dec2base(old_ind, r)), r); //it works only on octave
old_ind_base = dec2base(old_ind, r) ;
new_ind_base = [] ;
b = [] ;
for i=1:length(x)
new_ind_base = [new_ind_base mtlb_fliplr(old_ind_base(i))];
end
new_ind = base2dec(new_ind_base,r) ;
//end of index conversion
i = new_ind + 1;
y(old_ind + 1) = x(i);
[rows_x columns_x] = size(x) ;
if (columns_x == 1)
y = y';
else
i = i;
end
endfunction
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