bitrevorder() - Signal Processing

bitrevorder is useful
for pre-arranging filter coefficients so that bit-reversed ordering
does not have to be performed as part of an fft or
inverse FFT (ifft) computation.
This can improve run-time efficiency for external applications or
for Simulink® blockset models. Both MATLAB® fft and ifft functions
process linear input and output. Note  


Using bitrevorder is equivalent to using digitrevorder with radix base 2.y = bitrevorder(x) returns
the input data in bit-reversed order in vector or matrix y.
The length of x must be an integer power of 2.
If x is a matrix, the bit-reversal occurs on the
first dimension of x with size greater than 1. y is
the same size as x. [y,i] = bitrevorder(x) returns
the bit-reversed vector or matrix y and the bit-reversed
indices i, such that y = x(i). Recall that MATLAB matrices use 1-based
indexing, so the first index of y will be 1, not
0.The following table shows the numbers 0 through 7, the corresponding
bits, and the bit-reversed numbers.Linear IndexBitsBit- ReversedBit-Reversed
Index
00000000
10011004
20100102
30111106
41000011
51011015
61100113
71111117

Syntax

y = bitrevorder(x)[y,i] = bitrevorder(x)

Example

Vector in Bit-Reversed OrderOpen This Example
Create a column vector and obtain its bit-reversed version. Verify by displaying the elements as binary strings.
x = (0:15)';
v = bitrevorder(x);

x_bin = dec2bin(x);
v_bin = dec2bin(v);

T = table(x,x_bin,v,v_bin)

T = 

    x     x_bin    v     v_bin
    __    _____    __    _____

     0    0000      0    0000 
     1    0001      8    1000 
     2    0010      4    0100 
     3    0011     12    1100 
     4    0100      2    0010 
     5    0101     10    1010 
     6    0110      6    0110 
     7    0111     14    1110 
     8    1000      1    0001 
     9    1001      9    1001 
    10    1010      5    0101 
    11    1011     13    1101 
    12    1100      3    0011 
    13    1101     11    1011 
    14    1110      7    0111 
    15    1111     15    1111

Output / Return Value

Limitations

Alternatives / See Also

Reference