Mercurial > hg > octave-lojdl
changeset 7697:0bdfff62cc49
lsqnonneg: use optimset, correctly index Z and P in main loop
author | bill@denney.ws |
---|---|
date | Thu, 03 Apr 2008 07:43:59 -0400 |
parents | 0a362fa8f3c8 |
children | 4584feed3ec4 |
files | scripts/ChangeLog scripts/optimization/lsqnonneg.m |
diffstat | 2 files changed, 32 insertions(+), 17 deletions(-) [+] |
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--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,8 @@ +2008-04-04 Bill Denney <bill@denney.ws> + + * optimization/lsqnonneg.m: Use optimset, correctly index + Z and P in main loop. + 2008-04-04 David Bateman <dbateman@free.fr> * deprecated/beta_cdf.m deprecated/beta_inv.m
--- a/scripts/optimization/lsqnonneg.m +++ b/scripts/optimization/lsqnonneg.m @@ -56,65 +56,75 @@ ## @seealso{optimset} ## @end deftypefn -## This is implemented from Lawson and Hanson's 1973 algorithm on page +## This is implemented from Lawson and Hanson's 1973 algorithm on page +## 161 of Solving Least Squares Problems. function [x, resnorm, residual, exitflag, output, lambda] = lsqnonneg (c, d, x = [], options = []) + ## Lawson-Hanson Step 1 (LH1): initialize the variables. if (isempty (x)) - ## initial guess is 0s + ## Initial guess is 0s. x = zeros (columns (c), 1); endif if (isempty (options)) - ## FIXME: Optimset should be updated - ## options = optimset (); - options = struct ("maxiter", 1e5, "tolx", 1e-8); + ## FIXME: what are the correct defaults? + options = optimset ("maxiter", 1e5, "tolx", 1e-8); endif - ## Initialize the values + ## Initialize the values. p = []; z = 1:numel (x); - ## compute the gradient + ## LH2: compute the gradient. w = c'*(d - c*x); iter = 0; - while (! isempty (z) && any (w(z) > 0) && iter < options.maxiter) + ## LH3: test for completion. + while (! isempty (z) && any (w(z) > 0) && iter < options.MaxIter) + ## LH4: find the maximum gradient. idx = find (w == max (w)); if (numel (idx) > 1) warning ("lsqnonneg:nonunique", "A non-unique solution may be returned due to equal gradients."); idx = idx(1); endif - p(end+1) = z(idx); - z(idx) = []; + ## LH5: move the index from Z to P. + z(z == idx) = []; + p(end+1) = idx; newx = false; - while (! newx && iter < options.maxiter) + while (! newx && iter < options.MaxIter) iter++; + ## LH6: compute the positive matrix and find the min norm solution + ## of the positive problem. cpos = c; cpos(:,z) = 0; - ## find min norm solution to the positive matrix + ## Find min norm solution to the positive matrix. [cpos_q, cpos_r] = qr (cpos, 0); xtmp = (cpos_r\cpos_q')*d; xtmp(z) = 0; if (all (xtmp >= 0)) - ## complete the inner loop + ## LH7: tmp solution found, iterate. newx = true; x = xtmp; else + ## LH8, LH9: find the scaling factor and adjust X. mask = (xtmp < 0); - alpha = min(x(mask)./(x(mask) - xtmp(mask))); + alpha = min (x(mask)./(x(mask) - xtmp(mask))); + ## LH10: adjust X. x = x + alpha*(xtmp - x); + ## LH11: move from P to Z all X == 0. idx = find (x == 0); - p(ismember (p, x)) = []; + p(ismember (p, idx)) = []; z = [z idx]; endif endwhile w = c'*(d - c*x); endwhile + ## LH12: complete. - ## generate the additional output arguments + ## Generate the additional output arguments. if (nargout > 1) resnorm = norm (C*x-d) ^ 2; endif @@ -122,7 +132,7 @@ residual = d-C*x; endif exitflag = iter; - if (nargout > 3 && iter >= options.maxiter) + if (nargout > 3 && iter >= options.MaxIter) exitflag = 0; endif if (nargout > 4)