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bbmatrix Create a black-box operator from a matrix. BB=bbmatrix(A) encapsulates the Matlab-matrix A, full or sparse, in a black-box matrix. This is a handy way to treat sparse matrices, which are ubiquitous in large-scale computations. In most cases a product between a black-box operator and a Matlab-matrix returns a dense matrix for the sake of compatibility. To avoid this, all arguments should be transformed to black-box form. BB=bbmatrix(A,'notol') creates a black-box without estimating the accuracy of the product. This will reduce the construction time slightly, but also limits the applicable iterative algorithms. Example: A=randn(1000,1); B=randn(1,1000); C1=A*B; C2=bbmatrix(A)*B; C3=bbmatrix(A)*bbmatrix(B); whos C1 C2 C3 >> Name Size Bytes Class >> C1 1000x1000 8000000 double array >> C2 1000x1000 8000000 double array >> C3 1000x1000 22071 blackbox object See also blackbox.