W'*X*X'*W or W'*(X*X')*W, which one is more precision
显示 更早的评论
Hi everyone.
When I wrote something like W'*X*X'*W, matlab gives me hint that parenthese X. I did a lot of experiment, when W is a big size matrix and the value of the element in W is small, these two equations give me different results. I'm wondering which one is more precision?
THanks
2 个评论
Pourya Alinezhad
2013-8-9
编辑：Pourya Alinezhad
2013-8-9
i think this is the output power of an adaptive array or a tapped delay line filter or something like that... so you need to calculate p=y*y' so write :
p=(W*X')*(W*X')'
or
k=W*X';
p=k*k';
Jan
2013-8-10
@zhang: To be exact, both have the same precision, namely double precision. You mean accuracy. The difference is essential.
回答（1 个）
Jan
2013-8-10
3 个投票
The gained accuracy depends on the data also. You can check this applying small variations to the input and measure the changes in the output. This determines the sensitivity of the implementation.
类别
在 帮助中心 和 File Exchange 中查找有关 Functions 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
