How can I display the second derive of a vector ,?

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Mallouli Marwa
Mallouli Marwa 2018-6-27
评论： Mallouli Marwa 2018-6-28
Hello
How can I display the second derive of a vector ?
Mention that I have this table and I want to obtain the second derive of the second column of the table.
Thanks
  2 个评论
Jan
Jan 2018-6-27
What exactly is the problem? Importing the file, extracting the 2nd column or using gradient twice?
Mallouli Marwa
Mallouli Marwa 2018-6-27
Yes Importing the file, extracting the 2nd column and calculating
gradient twice of this column

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采纳的回答

Jan
Jan 2018-6-28
gradient(gradient(data(:,2)));

更多回答（1 个）

Mark Saad
Mark Saad 2018-6-27
编辑：Mark Saad 2018-6-27
You can first import it into MATLAB as an array using textread.
data = textread('essai_Al_but05_fixe_100Ohm.txt');
Then just access elements using data(i,j) where i is the row and j is the column. So if you want the second element in the third row, you do
data(3,2);
If you want the entire third row, you do
data(3,:);
Or if you want the entire second column,
data(:,2);

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