Assign Values to Each Element of Symbolic Array

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Kevin Bachovchin
Kevin Bachovchin 2014-5-12
评论： Deepak Ramaswamy 2014-5-14
Hello,
I have an array of symbolic values and I want to assign values to each symbolic variable in the array?
For example if I have
syms x1 x2 x3 x4 x5
X = [x1 ; x2 ; x3 ; x4 ; x5];
Values = [1 ; 2 ; 3 ; 4 ; 5];
I want to assign each symbolic element of X equal to the corresponding number in Values (in this case x1 = 1, x2 = 2, etc). Is there a way to do this?
X = deal(values) does NOT work because it assigns X = [1 ; 2 ; 3 ; 4 ; 5] rather than x1 = 1, x2 = 2, x3 = 3, x4 = 4, x5 = 5 like I want
Thank you,
Kevin

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Deepak Ramaswamy
Deepak Ramaswamy 2014-5-14
编辑：Deepak Ramaswamy 2014-5-14
I really don't like this solution at all but does this work for you?:
syms x1 x2 x3 x4 x5
X = [x1 x2 x3 x4 x5].';
values = [1 2 3 4 5].';
for k = 1:numel(X)
eval(sprintf('%s=values(%d)',char(X(k)),k));
end
This creates x1 x2 etc in the MATLAB workspace
  2 个评论
Kevin Bachovchin
Kevin Bachovchin 2014-5-14
That does work. However, if I want to substitute in numerical values in expressions that contain x1, x2, etc, I need to use the "subs" command.
NewExpr = subs(OldExpr, X, values)
The "subs" command is pretty inefficient from what I see though. I think I'm better off creating a function handle from the symbolic expression using the "matlabFunction" command.
Deepak Ramaswamy
Deepak Ramaswamy 2014-5-14
I agree using matlabFunction() whenever the symbolic expression is "set" (i.e. there is no need for further symbolic operations) will provide better performance.

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