sub2ind, ind2sub

sub2ind

ind = sub2ind(sz,I1,...,In) returns the linear indices ind corresponding to multidimensional subscripts I1, …, In for a multidimensional array of size sz
- Here sz is a vector with n (or greater than n) elements that specifies the size of each array dimension
- 返回的都是元素的 single linear index
- I1, …, In 为长度相同 vector

The mapping from subscripts (indexing by position) to linear indices for a 3-by-3 matrix can be illustrated as in the following.

Specify the row and column subscripts in a 3-by-3 matrix. Convert the subscripts to linear indices.

>> row = [1 2 3 1];
>> col = [2 2 2 3];
>> sz = [3 3];
>> ind = sub2ind(sz,row,col)
ind =
    4     5     6     7

[I1,I2,...,In] = ind2sub(sz,ind) returns n arrays I1, …, In containing the equivalent multidimensional subscripts corresponding to the linear indices ind for a multidimensional array of size sz
- Here sz is a vector with n elements that specifies the size of each array dimension
- ind 需为 single indices 组成的 vector 或 scalar