MATLAB: Sparse matrix

matricesmatrixsparsparse

I am trying out to form a sparse matrix but it runs out of memory.Below is the code similar to which I have been working on A=sparse(15000,15000); inb=sparse(eye(10000,10000); it goes out of memory here.

So for forming a identity matrix (inb) I use: inb=sparse(10000,10000); for i=1:1:10000; inb(i,i)=ones; end A(1:10000,1:10000)=inb; it goes out of memory. Is there any way I can get rid of this.

Best Answer

blkdiag(speye(30886,30886),sparse(68709-30886,130478-30886));

Related Solutions

MATLAB: How to find all the eigenvectors of a very large, sparse, symmetric, positive-definite matrix in MATLAB 7.8 (R2009a)

You are receiving the out of memory error because EIGS tries to return all of the eigenvectors at once and it is not possible to store all the 22500 eigenvectors on a 32-bit machine.

As a workaround, knowledge of the eigenvalues can be used to access the eigenvectors in chunks using the function EIGS as follows:

[V D] = eigs(A,100,0);

The above code will give 100 eigenvectors corresponding to eigenvalues closest to 0. For better results, never use an eigenvalue as the shift (third argument in EIGS).

When retreiving the eirgenvectors, note that although the matrix is sparse the eigenvectors are most likely dense.

MATLAB: Sparse Matrix – More Efficient Assignment Operation

That operation took less than 3 milliseconds on my machine.

The resulting array is 960,008 bytes.

Best Answer

Related Solutions

MATLAB: How to find all the eigenvectors of a very large, sparse, symmetric, positive-definite matrix in MATLAB 7.8 (R2009a)

MATLAB: Sparse Matrix – More Efficient Assignment Operation

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