size
(Not Recommended) Size of dataset array
The dataset data type is not recommended. To work with heterogeneous data,
        use the MATLAB®
        table data type instead. See MATLAB
        table documentation for more information.
Syntax
D = SIZE(A)
[NOBS,NVARS] = SIZE(A)
[M1,M2,M3,...,MN] = SIZE(A)
M = size(A,dim)
Description
D = SIZE(A) returns the two-element row vector
                D = [NOBS,NVARS] containing the number of observations
            and number of variables in the dataset A. A dataset array always has
            two dimensions.
[NOBS,NVARS] = SIZE(A) returns the numbers of observations and
            variables in the dataset A as separate output variables.
[M1,M2,M3,...,MN] = SIZE(A), for
                N > 2, returns
                M1 = NOBS, M2 = NVARS, and
                M3,..,MN = 1.
M = size(A,dim) returns the length of the dimension specified by
            the scalar dim:
- M = size(A,1)returns- NOBS
- M = size(A,2)returns- NVARS
- M = size(A,k)returns- 1for- k > 2