bitget
Extracts from integers bits of given indices
Syntax
y = bitget(x, pos)
Parameters
 x
 Scalar, vector, matrix or hypermatrix of positive decimal or encoded integers.
 pos
 Scalar, vector, matrix or hypermatrix of decimal or encoded integers in
[1, bitmax]
wherebitmax
is the maximal index of bits for the type ofx
: Indices of bits to be extracted. The bit #1 is the lightest one (2^{0}).typeof(x) bitmax .. typeof(x) bitmax int8 7 uint8 8 int16 15 uint16 16 int32 31 uint32 32 int64 63 uint64 64 decimal 1024  y
Scalar, vector, matrix or hypermatrix of 0 and 1 of the type of
x
. The sizes and contents ofy
are as follows:If
x
is a scalar:y
has the sizes ofpos
y(i,j,..)
is the value of bit #pos(i,j,..)
ofx
.
If
pos
is a scalar:y
has the sizes ofx
y(i,j,..)
is the value of the bit #pos
ofx(i,j,..)
.
If
x
andpos
are arrays with identical sizes, the processing is elementwise:y
has the sizes ofx
andpos
y(i,j,..)
is the value of the bit #pos(i,j,..)
ofx(i,j,..)
.
Otherwise:
y
is a matrix withlength(x)
rows andlength(pos)
columns.y(i,j)
is the value of the bit #pos(j)
ofx(i)
.
Description
bitget()
scans chosen bits of the binary representation of some
positive integers x
. It returns 0 for bits down, and 1 for bits up.
The result has the sizes of x
or of pos
or
of both inputs.
However, when both x
and pos
are nonscalar and
have mismatching sizes, the result y
is a matrix ignoring the sizes
of x
. Then, after reshaping y
with
y = matrix(y, [size(x) 1])
, the value of the bit #b of
x(i,..,k)
is in y(i,..,k,b)
.
Examples
// 19 is (10011)_2 // The 2nd bit is 1 (starting from the end). x = uint8(19); pos = 2; y = bitget(x,pos) expected = 1; // 13 is (1101)_2 dec2bin(13) bitget(uint8(13),4:1:1)
With encoded integers:
> b = [1 3 8 11 15]; > x = sum(int16(2).^(b1)) x = 17541 > B = bitget(x, 1:15) B = 1 0 1 0 0 0 0 1 0 0 1 0 0 0 1 > find(B) ans = 1. 3. 8. 11. 15. > typeof(B) ans = "int16"
With uint64 integers > 2^{52}:
> b = [1 12 23 34 45 53 64]; > x = sum(uint64(2).^(b1)) x = 9227893237262321665 > B = bitget(x, 1:64) B = column 1 to 32 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 column 33 to 64 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 > find(B) ans = 1. 12. 23. 34. 45. 53. 64. > typeof(B) ans = "uint64"
With big decimal integers > 2^{52}:
x = sum(2 .^([7 16 18 19 25 52 70]1)) bitget(x, [7 16 18 19 35 52 70 80])
> x = sum(2 .^([7 16 18 19 25 52 70]1)) x = 5.903D+20 > bitget(x, [7 16 18 19 35 52 70 80]) ans = Nan Nan 1. 1. 0. 1. 1. 0.
x and pos are arrays with mismatching sizes:
x = [ 39 6 62 8 14 29 4 64 12 44 39 50 52 12 39 5 4 29 ]; x = sum(2.^(x1),2); bitget(x, [5 8 12 39])
> bitget(x, [5 8 12 39]) ans = Nan Nan 0. 1. 0. 1. 0. 0. Nan Nan 1. 0. 0. 0. 0. 1. 0. 0. 1. 1. 1. 0. 0. 0.
See Also
 bitstring — A string giving the literal bit representation of a number
 dec2bin — convert from decimal to binary
 bitset — Sets bits of given indices in some integers
 bitand — bitwise logical AND between elementwise integers of 2 arrays
 & — Binary AND between integers. Logical AND over/between booleans and numbers
History
Version  Description 
6.1 

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