Finding a value in a column from a change in another column in a matrix?

Question

Matilde Garcia 2015-12-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/258622-finding-a-value-in-a-column-from-a-change-in-another-column-in-a-matrix

评论： Matilde Garcia 2015-12-3

Given the matrix below:

1586    0.9381    3.0000         
2265    0.6906    3.0000       
2765    0.5432    3.0000        
3266    0.4243    2.9999        
3766    0.3302    2.9999      
4267    0.2565    2.9997

How can I write the code which gives me the value in column 1, corresponding to the point in which column 3 changes from 3.0000 to 2.9999?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Thorsten 2015-12-3

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/258622-finding-a-value-in-a-column-from-a-change-in-another-column-in-a-matrix#answer_202074

编辑：Thorsten 2015-12-3

在 MATLAB Online 中打开

ind =  X(:,3) == 3.0 & [abs(abs(diff(X(:,3))) - 1e-4) < 1e-10; 0]
X(ind,1)

or

ind =  X(1:end-1,3) == 3.0 & X(2:end,3) == 2.9999;
X(ind, 1)

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Matilde Garcia 2015-12-3

Thanks for the help

请先登录，再进行评论。

Answer 2

Eng. Fredius Magige 2015-12-3

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/258622-finding-a-value-in-a-column-from-a-change-in-another-column-in-a-matrix#answer_202072

编辑：Eng. Fredius Magige 2015-12-3

Hi Use for in association with find function looking exact Nii_Ni=0.0001; note the last and first N need some manipulation, this could be controlled by if else