## bbsolveopt

This function is not yet fully documented. This is a transcript of
the text-formatted help.

bbsolveopt Create parameters for solving a linear syste,
bbsolveopt(A) creates a set of parameters suitable for solving the
linear system A*X=B.
Syntax:
OPT2=bbsolveopt(A)
OPT2=bbsolveopt(A,REG)
OPT2=bbsolveopt(A,OPT1)
OPT2=bbsolveopt(A,REG,OPT1)
bbpresolve, bbsolve, and bbregsolve are flexible tools, which can
be controlled by parameters given in a struct. bbsolveopt is
intended for the case where it is necessary to tune a computation.
Instead of creating a set of parameters from scratch, bbsolveopt
creates the required parameters which can be used as a starting point.
Fields in OPT1 are passed unmodified in OPT2. Therefore, you may fill
in some fields, and let bbsolveopt choose any unspecified parameters.
These will, in general, depend on the parameters present in OPT1.
The most useful options are the following:
reg Enable regularized solutions [true | {false}]
tol Solution tolerance [scalar | {1e-6}]
ntol Null-space tolerance [scalar | {tau}]
rmaxi Maximum number of restarts [integer | inf | {30}]
mem Available memory in megabytes [scalar]
disp Verbosity level [-1 | 0 | {1} | 2]
TOLERANCE: an unregularized solution, A*X=B+Z, should satisfy:
norm(A*X+Z-B) <= OPT.tol (accuracy of the solution)
norm(A'*Z) <= OPT.ntol*norm(Z) (definition of null-space)
REGULARIZATION: to compute regularized solutions, is is necessary to
set OPT.reg=true. The following options is also respected:
rtol Relative tolerance [scalar | {0.1}]
atol Absolute tolerance [scalar | {tau}]
For reliable results, the singular triplets must be computed with some
accuracy, which is controlled by OPT.rtol. The appropriate value
depends on the steepness of the filter-factors used for regularization.
A component is also accepted if the absolute accuracy is better than
OPT.atol. If it is known that the filter-factors will damp out singular
values below some threshold, setting OPT.atol and OPT.ntol may save
a substantial amount of computation.
TUNING: It is possible to control the inner workings more precisely.
The main reason for doing this is to reduce the memory used.
K Dimension of the workspace [integer]
rkeep Ideal dimension of the workspace [integer]
These are subject to change. Please consult the manual for details.
See also bbpresolve, bbsolve, bbregsolve.

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