How to take the square of every single value in the code below

Hi,

I am using the code below in which the line

col_13_data(:,i) = table2array( data(:,13) );

producing 48x79 double

I want to take the square of each value that is produced, how would I proceed this.

I am pasting the code below with the error I am encountering.

Code:

close all; clear all; clc;

P = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side_LSB\Length\DesignPoint\110_outlet';

Q = 'F:\3-PIV_Experimental_Data\Calculations_TurbulentIntensity\line_Data\Elliptical_Side_LSB\Length\DesignPoint';

S = dir(fullfile(P,'*.csv'));

N = natsortfiles({S.name});

TurbulentFluctuationArray_Mean=zeros(numel(N), 1);

col_13_data = zeros(48,numel(N))

col_13_data_Square = zeros(48,numel(N))

for i = 1:numel(N);

data = readtable( fullfile(P, N{i}) ); % read the csv files

col_13_data(:,i) = table2array( data(:,13) ); % get the 13th column of each file

col_13_data_Square = table2array( data(:,13).^2 )

end

Error:

Operator '.^' is not supported for operands of type 'table'.

Error in Extracting_Column (line 15)

col_13_data_Square = table2array( data(:,13).^2 )

Answer 1

[Voss]

Use {} to get the values out of the table:

for i = 1:numel(N);
    data = readtable( fullfile(P, N{i}) ); % read the csv files
    col_13_data_Square(:,i) = data{:,13}.^2;
end

[muhammad choudhry]

that's perfectly work. Just wondering is there specific reason it did not work with () but worked with the {} brackets.

[Voss]

Using parentheses () to index a table gives you another table:

t = table([1;2;3],[4;5;6]) % a table with two columns

t = 3×2 table
    Var1    Var2
    ____    ____

     1       4  
     2       5  
     3       6  

new_t = t(:,2) % a table with one column

new_t = 3×1 table
    Var2
    ____

     4  
     5  
     6  

class(new_t)

ans = 'table'

On the other hand, using curly braces {} extracts the values from the column(s) of the table:

new_t = t{:,2} % a numeric column vector

new_t = 3×1

4 5 6

class(new_t)

ans = 'double'