String manipulation (change of a string in a loop)

Hi, I have a function f(x1,x2,x3), I want to explore the sensitivity of each parameters on the function f. I wrote the code (is not relay the code but a description)

variabDim=val;
x1=val1; x2=val2;x3=val3; real values of the variables
UB=[val1,val2,val3]; Lower bound for the variables
LB=[val1,val2,val3]; Upper bound for the variables
for i =1:variabDim
for x1 = LB(i):(UB(i)-LB(i))/numpoint:UB(i)
x= [x1,x2,x3];
f(x); 
end
what I want to ask is, how can I make the string x1 change in the second loop to x2 and x3 with the change of i.

[boureghda mohammed]

The important to me from this question is how can I make the string x1 to change in the second loop to x2 and x3 with the change of i, for example in the code below how can I make param(1) in the second loop to be replaced by the variable x1 and so on.

param=[x1,x2,x3]
for i=1:variablDim
for param(i) = 0:0.01:10
x = [x1,x2,x3];
f(x);
end
end

Answer 1

[Steven Lord]

Don't think of it as changing a variable name. Think of it as changing which element of the vector you modify.

base = [1 2 3];
for whichElement = 1:3
  for newvalue = 5:10
    x = base;    
    x(whichElement) = newvalue;
    disp(x)
  end
end