Can someone please help me in creating a custom function for a formula as
follows:

=SUMPRODUCT(--(MOD(COLUMN(B1:N1),COLUMNS(A1:D1))=MOD(COLUMN(B1), COLUMNS(A1:D1))),B1:N1,--(MOD(COLUMN(C1:O1),COLUMNS(A1:D1))=MOD(COLUMN(C1), COLUMNS(A1:D1))),C1:O1)/SUMPRODUCT(--(MOD(COLUMN(B1:N1),COLUMNS(A1:D1))=MOD(COLUMN(B1), COLUMNS(A1:D1)))*--(C1:O10),B1:N1)

Like:

MyFormula( B1 , C1 , A1:D1 , B1:N1 , C1:O1 )

Following cell references may kindly be converted to variables:
B1 , C1 , A1:D1 , B1:N1 , C1:O1

Thanx!