Question

在Matlab中，有没有一种快速的方法用A和B块填充（稀疏）矩阵：

 A, B, 0, 0, 0
 B, A, B, 0, 0
 0, B, A, B, 0
 0, 0, B, A, B
 0, 0, 0, B, A

我尝试了此代码

e=full([A B; B A]);
e1=e;
for i=1:n
   e=blkdiag(e,e1);
end

Answer 1

您可以执行以下操作（将功能保存到文件blktritoep.m中）：

function C = blktritoep(A, B, nb)
% A, B must be square of and same size for this to work
% nb = number of times A gets repeated on the diagonal of C
A = sparse(A); % Does nothing if A is already sparse
B = sparse(B); % Idem
C = kron(diag(ones(nb,1)), A) + kron(diag(ones(nb-1,1), 1), B) + ...
    kron(diag(ones(nb-1,1), -1), B);
end

例如，我得到的输出

A = ones(2,2);
B = -2 * ones(2,2);
C = blktritoep(A, B, 3);
full(C) % Result is sparse, just for pretty printing!

是

ans =

     1     1    -2    -2     0     0
     1     1    -2    -2     0     0
    -2    -2     1     1    -2    -2
    -2    -2     1     1    -2    -2
     0     0    -2    -2     1     1
     0     0    -2    -2     1     1

如何从n个大小的块中制作一个块稀疏矩阵？

1 个答案: