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bbregsolve Compute a regularized solution for A*X=B. X=bbregsolve(S,T,...), where S is returned by bbpresolve, approximates a regularized solution using the filter-factors specified by T: 'none' - No regularization 'Tikhonov' - Tikhonov-regularization 'Ridge' - Alias for 'Tikhonov' 'dsvd' - Damped svd 'tsvd' - Truncated svd <interp> - Arbitrary filter-factors by interpolation Except for 'none', the standard regularization methods must be followed by a regularization parameter framed in terms of a singular value. In particular, the parameter given to 'tsvd' is a threshold for the singular value, not the number of singular triplets (of which bbregsolve have no knowledge). Normally, bbregsolve computes a hybrid solution, which is colored by the intrinsic filter-factors of the iterative routine. If T is prepended with '!', then bbregsolve will only use vectors that converged to the desired tolerance. Example: bbregsolve(S,'!tsvd',1e-2) computes a solution that approximates the truncated svd using only singular vectors with singular values of 1e-2 or higher. It only use triplets that converged to the specified tolerance. In principle a non-hybrid solution should be closer to the ideal solution. However, the method should only be applied when the singular space containing the solution have converged, and this often requires an impractically large number of iterations. A practical way to check this is to compute the regularized solution of type '!none'. If the residual is indistinguishable from noise, then a non-hybrid solution may be appropiate. Custom filter-factors may be specified by an interpolation-scheme compatible with interp1, a vector of singular values, and a vector with corresponding filter-factors. The interpolation will happen after taking the logarithm of the singular values. Example: sig=exp(-5:.1:0); xh=bbregsolve(S,'spline',sig,tanh(sig/.15)); See also bbpresolve, , bblcurve.