AUNSTACK

[Xlambda]

AUNSTACK unstack an array, calls AFLATTEN

=LAMBDA(a,h,
    LET(k,ABS(h),
       r,ROWS(a),
       c,COLUMNS(a),
       mo,MOD(r,k),
       nr,IF(mo,r+k-mo,r),
       sr,SEQUENCE(nr),
       na,IFERROR(INDEX(a,sr,SEQUENCE(,c)),""),
       nc,c*nr/k,
       snc,SEQUENCE(,nc),
       q,QUOTIENT(snc-1,c)+1,
      m,MOD(snc-1,c)+1,x,(q-1)*k*c+m+(SEQUENCE(k)-1)*c,
       f,AFLATTEN(na),
       rs,XLOOKUP(x,SEQUENCE(nr*c),f),
       IF(k>=r,a,rs)
    )
)

LAMBDA 5.0.xlsx
	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S
1	1	2	3			rows	18
2	4	5	6			clm.	3
3	7	8	9			unstack
4	10	11	12			6	1	2	3	19	20	21	37	38	39
5	13	14	15				4	5	6	22	23	24	40	41	42
6	16	17	18				7	8	9	25	26	27	43	44	45
7	19	20	21				10	11	12	28	29	30	46	47	48
8	22	23	24				13	14	15	31	32	33	49	50	51
9	25	26	27				16	17	18	34	35	36	52	53	54
10	28	29	30
11	31	32	33
12	34	35	36			5	1	2	3	16	17	18	31	32	33	46	47	48
13	37	38	39				4	5	6	19	20	21	34	35	36	49	50	51
14	40	41	42				7	8	9	22	23	24	37	38	39	52	53	54
15	43	44	45				10	11	12	25	26	27	40	41	42
16	46	47	48				13	14	15	28	29	30	43	44	45
17	49	50	51
18	52	53	54
19							1	2	3	22	23	24	43	44	45
20							4	5	6	25	26	27	46	47	48
21							7	8	9	28	29	30	49	50	51
22							10	11	12	31	32	33	52	53	54
23							13	14	15	34	35	36
24							16	17	18	37	38	39
25							19	20	21	40	41	42
26
AUNSTACK post

Cell Formulas
Range	Formula
A1:C18	A1	=SEQUENCE(G1,G2)
G4:O9	G4	=AUNSTACK(A1#,F4)
G12:R16	G12	=AUNSTACK(A1#,F12)
G19:O25	G19	=AUNSTACK(A1#,7)
Dynamic array formulas.