Negative indexing of an array

I have an array say x= [1 2 3 4 5 6] which means that x(1)=1 ,x(2)=2 and so on . I just what to shift this array in such a way that x(-3)=1 ,x(-2)=2, x(-1)=3 ....and so on . What to do??? Please help....

Answer 1

[Walter Roberson]

x = @(idx) x(idx+4)

This does appear to use the same "x" on the left side and the right side, but it does not really do so. At the time the anonymous function is created, the current value of the matrix x will be copied into the anonymous function handle, and afterwards the anonymous function will retrieve values from that copy.

This means that you can only use the above in expressions, not as the destination of an assignment. For example,

y = x(-2)    %would work
x(-2) = 7    %would fail

Answer 2

[Asad (Mehrzad) Khoddam]

There is no non-positive indexing in Matlab.

you can use x(end) for the last member, x(end-1) the member before the last member and so on.