# how can i return l21 value

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R jagadish on 14 Mar 2023
Answered: Dyuman Joshi on 14 Mar 2023
i am unable to return the l21 values as it is saved in a string format
here is my code:
syms l21 l31 l32 u11 u12 u13 u22 u23 u33
L=[1 0 0;l21 1 0;l31 l32 1]
L =
U=[u11 u12 u13;0 u22 u23;0 0 u33]
U =
B=L*U
B =
A=[2 -3 1;1 -1 -2;3 1 -1]
A = 3×3
2 -3 1 1 -1 -2 3 1 -1
x=solve(A==B,[l21,l31,l32,u11,u12,u13,u22,u23,u33])
x = struct with fields:
l21: 1/2 l31: 3/2 l32: 11 u11: 2 u12: -3 u13: 1 u22: 1/2 u23: -5/2 u33: 25
l21
l21 =

Dyuman Joshi on 14 Mar 2023
As you can see above, l21 is stored as a field in the struct x. You need to use dot indexing to get its value -
syms l21 l31 l32 u11 u12 u13 u22 u23 u33
L=[1 0 0;l21 1 0;l31 l32 1];
U=[u11 u12 u13;0 u22 u23;0 0 u33];
B=L*U;
A=[2 -3 1;1 -1 -2;3 1 -1];
x=solve(A==B,[l21,l31,l32,u11,u12,u13,u22,u23,u33])
x = struct with fields:
l21: 1/2 l31: 3/2 l32: 11 u11: 2 u12: -3 u13: 1 u22: 1/2 u23: -5/2 u33: 25
%Accessing field values via dot indexing
x.l21
ans =
x.u11
ans =
2