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Part(s) of almost block-diagonal matrix


[nb,rows,ncols,last,blocks] = bkbrk(blokmat)


[nb,rows,ncols,last,blocks] = bkbrk(blokmat) returns the details of the almost block-diagonal matrix contained in blokmat, with rows and last nb-vectors, and blocks a matrix of size [sum(rows),ncols].

This utility program is not likely to be of interest to the casual user. It is used in slvblk to decode the information, provided by spcol, about a spline collocation matrix in an almost block diagonal form especially suited for splines. But bkbrk can also decode the almost block-diagonal form used in [1].

bkbrk(blokmat) returns nothing, but the details are printed out. This is of use when trying to understand what went wrong with such a matrix.


[1] C. de Boor and R. Weiss. “SOLVEBLOK: A package for solving almost block diagonal linear systems.” ACM Trans. Mathem. Software 6 (1980), 80–87.

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