How can I create variables from a matrix (4 x m), so that every column is a variable ? In the code I have 2 elements (N=2), but I need to do it also with 6, 8 10 elements.

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Arthur Morais
Arthur Morais 2021-10-2
编辑： Ravi Narasimhan 2021-10-2
N=2; % elements
L=1/N;
L=zeros(1,N)+L;
y=0:L:1;
Nf=NaN;
syms x NaN
for i=1:length(y)
if i-1==0
fa(i)=NaN;
elseif i-1==1
fa(i)=NaN;
else fa(i)=0;
end
if i-1==0
fb(i)=NaN;
else
fb(i)=(x-y(i-1))/L(i-1);
end
if i+1>N+1
fc(i)=NaN;
else
fc(i)=(y(i+1)-x)/L(i);
end
if i+1>=N+1
fd(i)=Nf;
else
fd(i)=0;
end
end
f=[fa; fb; fc; fd]
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DGM
DGM 2021-10-2
编辑：DGM 2021-10-2
This is relevant.
https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
Long story short: arrays are indexable programmatically. Variable names are not programmatically indexable without opening up a can of worms that you should want to avoid unless you actually like causing problems for yourself.
As dpb mentioned, there are options like structs or tables that might be more desirable for the way they allow you to describe and organize their contents.
Ravi Narasimhan
Ravi Narasimhan 2021-10-2
编辑：Ravi Narasimhan 2021-10-2
Ran in:
To pile on: I use tables a lot but also Map Containers for associating keys with values when appropriate.
e.g.
A = magic(4)
A = 4×4
16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1
keySet = [1,2,3,4]; % Can be almost anything including chars if desired
valueSet = {A(:,1), A(:,2), A(:,3), A(:,4)}; % Associate a value with each key
B = containers.Map(keySet, valueSet)
B =
Map with properties: Count: 4 KeyType: double ValueType: any
B(3)
ans = 4×1
3 10 6 15
B(22) = [1 0 1 0] % Add to it. The 22 is a key vs. an array element
B =
Map with properties: Count: 5 KeyType: double ValueType: any
keys(B)
ans = 1×5 cell array
{[1]} {[2]} {[3]} {[4]} {[22]}
values(B)
ans = 1×5 cell array
{4×1 double} {4×1 double} {4×1 double} {4×1 double} {[1 0 1 0]}
Further details are available at https://www.mathworks.com/help/matlab/map-containers.html

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