# How To change Diagonal Elements with a string in matrix using FOR loop or other preferred method?

10 views (last 30 days)
Faisal on 24 Sep 2022
Answered: David Hill on 24 Sep 2022
the result is to have a square matrix with a string e.g. "A" as diagonal elements using FOR LOOP
example:
M =
A 0 0 0 0
0 A 0 0 0
0 0 A 0 0
0 0 0 A 0
0 0 0 0 A
or How can I Print my name like ALEX diagonally
example;
M =
A 0 0 0
0 L 0 0
0 0 E 0
0 0 0 X
Here is My code that gives a specific number I assigned to variable in loop; however when that number is replaced with string it results NAN value as Diagonal elements.
clc
clear
clear all
m=5;
n=5;
a=zeros(m,n);
for i=1:m
for j=1:n
if i==j
a(i,j)= 5 ;
else
a(i,j)=0;
end
end
end
disp(a)
5 0 0 0 0 0 5 0 0 0 0 0 5 0 0 0 0 0 5 0 0 0 0 0 5
clc
clear
clear all
m=5;
n=5;
a=zeros(m,n);
for i=1:m
for j=1:n
if i==j
a(i,j)= "A" ;
else
a(i,j)=0;
end
end
end
disp(a)
NaN 0 0 0 0 0 NaN 0 0 0 0 0 NaN 0 0 0 0 0 NaN 0 0 0 0 0 NaN
Turlough Hughes on 24 Sep 2022
You can't mix characters or string values into an array of type double like that. On the otherhand, you can atleast represent numbers in a string array. Seeing as this is an exercise, I'm just going to nudge you towards a solution. Try starting with the following:
a = string(zeros(5))
a = 5×5 string array
"0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0" "0"

David Hill on 24 Sep 2022
a='ALEX';
b=diag(double(a));
b(b==0)=48;
string(char(b))
ans = 4×1 string array
"A000" "0L00" "00E0" "000X"
char(b)
ans = 4×4 char array
'A000' '0L00' '00E0' '000X'