Could I trust Matlab?
显示 更早的评论
Hello, I recently write a code and debug it.
I have a key sentence,
if true
% code
end while 1
...
if f(x_new)-f(x_old)<0
break;
elseif
L=1.1*L;
...
end
But it seems that the returned L is always wrong. And it always happened when f(x_new)-f(x_old)=1e-20. So I doubt maybe it should that f(x_new)<f(x_old), but the returned values is a little wrong to lead f(x_new)-f(x_old)=1e-20.
Could this thing happen in matlab.
Thank you in advance. I have already spent a lot time on it.
2 个评论
Jos (10584)
2013-12-4
编辑:Jos (10584)
2013-12-4
Based on this snippet, I have no idea what f, L, x_new and x_old are doing inside the loop. Are they being updated on the fly? And how do you know the returned L is wrong?
The elseif statement also seems out of place ...
Vivian
2013-12-4
回答(2 个)
Jos (10584)
2013-12-4
编辑:Jos (10584)
2013-12-4
Perhaps this is what you really want
if abs(f(x_new)-f(x_old)) < eps
…
end
Andreas Goser
2013-12-4
0 个投票
Looks like yet another flavor of the numerical question with the highest volume: http://www.mathworks.com/matlabcentral/answers/102419-how-do-i-determine-if-the-error-in-my-answer-is-the-result-of-round-off-error-or-a-bug
类别
在 帮助中心 和 File Exchange 中查找有关 Programming 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!