how to create a vector A [1,1,2,2,3,3] from a vector B [1,2,3]

REPELEM Replicate elements of an array. U = REPELEM(V,N), where V is a vector, returns a vector of repeated elements of V. - If N is a scalar, each element of V is repeated N times. - If N is a vector, element V(i) is repeated N(i) times. N must be the same length as V. B = repelem(A, R1, ..., RN), returns an array with each element of A repeated according to R1, ..., RN. Each R1, ..., RN must either be a scalar or a vector with the same length as A in the corresponding dimension. Example: If A = [1 2; 3 4], then repelem(A, 2, 3) returns a matrix containing a 2-by-3 block of each element of A: [1 1 1 2 2 2; ... 1 1 1 2 2 2; ... 3 3 3 4 4 4; ... 3 3 3 4 4 4]. See also REPMAT, BSXFUN, MESHGRID. Documentation for repelem doc repelem Other functions named repelem codistributed/repelem symfun/repelem tall/repelem gpuArray/repelem tabular/repelem