change specific col and row in a matrix

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Hi, let say i have matrix A=[20 40 60 70; 10 20 30 40; 60 50 20 10]. I want to change value in these location (e.g (2,2),(3,2),(1,4)) to 5 without having typing one by one to change the value.. how i can do that?
  1 Comment
Tiasa Ghosh
Tiasa Ghosh on 27 Aug 2018
do you have a pattern for the specific locations?

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Accepted Answer

KSSV
KSSV on 27 Aug 2018
A=[20 40 60 70; 10 20 30 40; 60 50 20 10] ;
r = [2 3 1] ;
c = [2 2 1] ;
B = A ;
% Method 1 , use loop
for i = 1:length(r)
A(r(i),c(i)) = 5 ;
end
% Method 2, use indices
idx = sub2ind(size(A),r,c) ;
B(idx) = 5 ;

More Answers (1)

Rita Barnabé
Rita Barnabé on 1 Nov 2021
Edited: Walter Roberson on 1 Nov 2021
Hi, how do I change all the values in a specific column ?
%Original values
ecg = Data (:,6);
n = 9; % Number of bits of the channel (?)
VCC = 3; % Operating voltage
Gecg = 1000; % Sensor gain
ecg_volts = (ecg/(2^n)-1/2)*VCC/Gecg;
and now i want to change ecg to ecg_volts value

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