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

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muhammad choudhry
muhammad choudhry 2022-6-17
评论： Voss 2022-6-18
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 )

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采纳的回答

Voss
Voss 2022-6-18
编辑：Voss 2022-6-18
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
  2 个评论
muhammad choudhry
muhammad choudhry 2022-6-18
that's perfectly work. Just wondering is there specific reason it did not work with () but worked with the {} brackets.
Voss
Voss 2022-6-18
Ran in:
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'

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