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

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

[Jan]

What exactly is the problem? Importing the file, extracting the 2nd column or using gradient twice?

[Mallouli Marwa]

Yes Importing the file, extracting the 2nd column and calculating

gradient twice of this column

Answer 1

[Jan]

gradient(gradient(data(:,2)));

[Mallouli Marwa]

Thanks

Answer 2

[Mark Saad]

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);

[Mallouli Marwa]

Then how can I calculate the gradient twice of this column ?