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Please help me how to describe a matrix in terms of smaller matrices.

Asked by Temesgen Gelaw on 28 May 2015
Latest activity Commented on by Temesgen Gelaw on 28 May 2015
For example,
Let A=[1 2 3; 4 5 6; 7 8 9 ] and
A11 = [ 1 2; 4 5] , A12 = [ 2 3 ; 5 6] , A21 = [ 4 5 ; 7 8], A22 = [ 5 6; 8 9]. So I wanted to express A in terms of A11, A12, A21, and A22.

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Answer by Michael Haderlein on 28 May 2015
 Accepted Answer

Is it sure they overlap by one line/column? Then it's just
A=[A11 A12(:,2:end);A21(2:end,:) A22(2:end,2:end)];

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yes. each adjacent matrices has 2 points in common.
Thank you !
Dear Michael I applied your method for A= 9x9 matrix as follows
A=[ A11(1:2,1:2) A12(1:2,2:3) A13(1:2,3:4) A14(1:2,4:5) A15(1:2,5:6) A16(1:2,6:7) A17(1:2,7:8) A18(1:2,8:end);
A21(2:3,1:2) A22(2:3,2:3) A23(2:3,3:4) A24(2:3,4:5) A25(2:3,5:6) A26(2:3,6:7) A27(2:3,7:8) A28(2:3,8:end);
A31(3:4,1:2) A32(3:4,2:3) A33(3:4,3:4) A34(3:4,4:5) A35(3:4,5:6) A36(3:4,6:7) A37(3:4,7:8) A38(3:4,8:end);
A41(4:5,1:2) A42(4:5,2:3) A43(4:5,3:4) A44(4:5,4:5) A45(4:5,5:6) A46(4:5,6:7) A47(4:5,7:8) A48(4:5,8:end);
A51(5:6,1:2) A52(5:6,2:3) A53(5:6,3:4) A54(5:6,4:5) A55(5:6,5:6) A56(5:6,6:7) A57(5:6,7:8) A58(5:6,8:end);
A61(6:7,1:2) A62(6:7,2:3) A63(6:7,3:4) A64(6:7,4:5) A65(6:7,5:6) A66(6:7,6:7) A67(6:7,7:8) A68(6:7,8:end);
A71(7:8,1:2) A72(7:8,2:3) A73(7:8,3:4) A74(7:8,4:5) A75(7:8,5:6) A76(7:8,6:7) A77(7:8,7:8) A78(7:8,8:end);
A81(8:end,1:2) A82(8:end,2:3) A83(8:end,3:4) A84(8:end,4:5) A85(8:end,5:6) A86(8:end,6:7) A87(8:end,7:8) A88(8:end,8:end)]
but not working. where is my mistake? Please show me !
Thank you Mr. Michael !

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