Bruno Luong

Not sure what advantage of conjgrad over Matlab builtin function LSQR (where preconditioning is possible):

x = lsqr(@afun,b);
    
function y = afun(x,transp_flag)
        if strcmp(transp_flag,'transp')
            y = A'*x;
        else
            y = A*x;
        end
    end

Marcello,

Do you have MEX setup? If not, type he following in command line:
>> mex -setup

If it's already installed you have to locate mexopts.bat file somewhere under the directory $MATLABROOT (where the Matlab is installed), then modify OPTPATH variable in line #8 and line #12 of GETMEXOPTS.

then try installation again.

Bruno

To make the function work for other integer class, I would suggest to modify the two lines:

d=diff([NaN; x]);
d=[true; d~=0];

to:

d=diff(x);
d=[true; d~=0];

Otherwise unexpected result is obtained with
[u p]=numunique(uint8([0 1]))

Beside the fact, that this is of practical use and works as expected, it helps to answer dozens of questions in the newsgroup: why does ANY((0:0.1:1) == 0.3) reply FALSE???
The help is complete and descriptive, contains author and date, exact and really useful comments. The H1-line is not helpful.
Minor bug in line 125: if ndims(A) ~= 2 || ndims(A) ~= 2. A simple [tf, loc] output might be more efficient than the VARARGOUT/Cell/DEAL/MIN/MAX/NARGOUT constructions.

PROBLEM: ismemberf([0 1 2], 0) will return [0 0 0]. It seems this is because line 263 will auto-configure tol to zero which causes unexpected results in ihi (line 274) that causes tf to be set incorrectly in line 276.

WORK-AROUND: This behavior can be avoided if 'tol' is explicitly set when calling ismemberf().