# Use results in the definition of my functions

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Florian Spicher on 17 Oct 2021
Commented: Star Strider on 17 Oct 2021
I would like to use my X(i)s to define my function p, but it says that they are undefined variables or functions. How can I do?
A=[46/15, 5/2, 2/3; 5/2, 8/3, 1; 2/3, 1, 2];
B=[2*exp(1); 2*exp(1); 2*exp(1)-2];
X=linsolve(A,B)
integral(@(x) f(x),0,1)
function p=p(x)
p=X(1)*x.^2+X(2)*x+X(3);
end
function f=f(x)
f=(exp(x)-p(x)).^2;
end
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### Accepted Answer

Star Strider on 17 Oct 2021
Try this instead —
function pv=p(X,x)
pv=X(1)*x.^2+X(2)*x+X(3);
end
Here, ‘X’ are the parameters and ‘x’ is the variable. Also, naming the variable inside the function to be the same as the function name confuses MATLAB (and everyone who reads the code).
Beyond that, what the problem and the desired result may be are both not possible to determine, and the parameters ‘X’ are nowhere either defined or calculated, so I’ll stop here.
.
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Star Strider on 17 Oct 2021
As always, my pleasure!
Since I don’t know the actual purpose of the code, I’m in no position to criticise its application. I’m just happy that I was able to help you get it to run! (I didn’t look carefully at the code the first time, so I didn’t notice that the ‘X’ parameters actually existed, and were calculated from the regression.)
.

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