From: Andrew Fitzgibbon <awf@ro...>  20020328 10:50:55

MATLAB will be fast for that matrix as it checks for symmetry (at the very least). Try A(i,i) = 1; A(i,i+1) = 2; A(i,i+2) = 1; > Original Message > From: vxlusersadmin@... > [mailto:vxlusersadmin@...] On Behalf Of > domi@... > Sent: 28 March 2002 10:44 > To: Vxlusers@... > Subject: Re: [Vxlusers] vnl_lsqr doesnt solve Ax=b > > > Well my feeling is that 2*n is enough. I get a good solution for > n=10,000 for 20,000 iterations. But it takes very long. Do you think I > could try using svd in my case to gain speed? > > > > > whereas for 30 equations it goes banana (wrong solution): > > > vnl_lsqr.cxx : The iteration limit ITNLIM was reached. > > > vnl_lsqr.cxx : iterations = 30 > > > > Could you try changing the # iterations to 120 in this case? > > > 60 already gave good results in my case. > > *I DONT KNOW IF THIS DOESNT DEPEND ON THE MATRIX* I used pretty naive > one: > > for (unsigned i=0; i<n; i++) { > A(i,i) = i+1.0; > b(i) = i+10.0; > } > > so the solution can be check by head. > > Domi > > > _______________________________________________ > Vxlusers mailing list > Vxlusers@... > https://lists.sourceforge.net/lists/listinfo/vxlusers > 