circshift function working explanation needed

Completely new to matlab. Studying some sample codes.

% bitget and num2str and circular shift
x = 0b10011010u8 % x is 10011010
value3= bitget(x, 8:-1:1) % x's binary representation is 10011010
formatSpec4= '%d'
s4= num2str(value3, formatSpec4);
s5= s4;
s5(1:4) = circshift(s5(1:4),-1);
s6= s5;

Not able to understand the syntax and functionality of circshift. Thank in advance

Please explain me the functionality of circshift.

Answer 1

[Voss]

circshift(s,d) for a vector s and positive integer d shifts the elements of s to the right by d amount, wrapping back to the beginning when they go off the end (thats why it's called circular). If d is negative, elements are shifted to the left by -d amount.

It's easier to see what it does with a few examples in MATLAB rather than a few sentences in English.

s = [10 20 30 40 50] % original vector s

s = 1×5

10 20 30 40 50

circshift(s,1) % shift s right by 1, last element wraps around to become first

ans = 1×5

50 10 20 30 40

circshift(s,-1) % shift s left by 1, first element wraps around to become last

ans = 1×5

20 30 40 50 10

circshift(s,2) % right by 2

ans = 1×5

40 50 10 20 30

circshift(s,-4) % left by 4

ans = 1×5

50 10 20 30 40

circshift(s,5) % shifting by the length of the vector returns the original vector

ans = 1×5

10 20 30 40 50

In your code, the first 4 elements of s5 are shifted left by one place and stored back into s5 as the first 4 elements (and the remaining elements are untouched):

s5 = [1 2 3 4 5 6 7 8]

s5 = 1×8

1 2 3 4 5 6 7 8

s5(1:4) = circshift(s5(1:4),-1)

s5 = 1×8

2 3 4 1 5 6 7 8

[Manu Chaudhary]

Thank you.

Answer 2

[Walter Roberson]

M = (10:10:40).' + (1:9)

M = 4×9

11 12 13 14 15 16 17 18 19 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39 41 42 43 44 45 46 47 48 49

circshift(M, -1)

ans = 4×9

21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39 41 42 43 44 45 46 47 48 49 11 12 13 14 15 16 17 18 19

You can see that this is the same as

[M(2:end,:); M(1,:)]

And more generally, circshift(M, -K) would be

[M(K+1:end,:); M(1:K,:)]

[Walter Roberson]

For vectors:

M = 1 : 9

M = 1×9

1 2 3 4 5 6 7 8 9

circshift(M, -1)

ans = 1×9

2 3 4 5 6 7 8 9 1

which is [M(2:end),M(1)] .

When you specify a scalar for the shift, then circshift operates on the first non-singleton dimension.

[Manu Chaudhary]

Thank you.