The log(dist) in the function causes the error message 'Matrix is singular, close to singular or badly scaled. Results may be inaccurate' How to make it work?

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Hashan 2017-9-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/356149-the-log-dist-in-the-function-causes-the-error-message-matrix-is-singular-close-to-singular-or-bad

编辑： Cedric 2017-9-11

 function f = polyharm(x, y, xj, yj, fj)
     p=size(x); 
     x = x(:);
     y = y(:);
     xj= xj(:);
     yj= yj(:);
     N = length(fj);
     [Xj, X] = meshgrid(xj,xj);
     [Yj, Y] = meshgrid(yj,yj);
     dist = (sqrt((X-Xj).^2 + (Y-Yj).^2));
     ndist = dist.^2.*log(dist);
     A = [zeros(3,3) [ones(N,1) xj yj]'
          ones(N,1) xj yj ndist];
     abc = A\[zeros(3,1); fj];
     [Xj, X] = meshgrid(xj,x);
     [Yj, Y] = meshgrid(yj,y);
     dist = (sqrt((X-Xj).^2 + (Y-Yj).^2));
     ndist = dist.^2.*log(dist);
     fc = abc(1) + abc(2)*x + abc(3)*y + ndist*abc(4:N+3); 
     f=reshape(fc,[p(1),p(2)]);
 end