work(x, xvector, fdata) Unrecognized function or variable 'x'.

function [a0,a1]=work(x,xvector,fvector)

fun=@(X,xdata) X(1)*exp(X(2)*xdata);

X0=rand(1,2);

A=lsqcurvefit(fun,X0,xvector,fvector);

fprintf('\n The answer for part a\n');

fprintf('\n V=%fe^(%f*P) \n',A(1),A(2));

fprintf('\n The answer for part b\n');

fprintf('The value of Volume at 1.05 bar by model is %f m^3\n',A(1)*exp(A(2)*x));

%Lagrange Method

xvalue = linspace(startingx, endingx, numberOfElements);

for i=1:length(xvector)

p=1;

for j=1:length(xvector)

if i~=j

p=p*((xvalue-xvector(j))/(xvector(i)-xvector(j)));

end

end

yvalue=yvalue+(p*fvector(i));

end

fprintf('\n The equation by Lagrange is:\n');

yvalue

fprintf('\n The answer for part c\n');

fprintf('The value of Volume at 1.5 bar by Lagrange is %f m^3\n',vpa(subs(yvalue,xvalue,x)));

fprintf('\n The answer for part d\n');

fprintf('\n The absolute difference between volume by predicted model and Lagrange interpolation is %f m^3\n',abs((A(1)*exp(A(2)*x))-(vpa(subs(yvalue,xvalue,x)))));

end

PLEASE CAN YOU HELP ME FIX THE ERROR (LINE 4)

Answer 1

[Image Analyst]

Evidently this is everyone's homework problem. Go here for a similar question:

https://www.mathworks.com/matlabcentral/answers/1633875-the-code-gives-error-can-you-help-me-to-correct-it-i-really-do-need-help?s_tid=srchtitle

and here

How do I get help on homework questions on MATLAB Answers? - MATLAB Answers - MATLAB Central

[Ali Aliev]

i saw your answer but it did not fixed the problem

[Image Analyst]

Well, what is x? You say that MATLAB says it's undefined. What did you assign to x when you called work()? So in your code:

x = ????????????
xVector = ??????????????
fvector = ???????????????
% Now call the function:
[a0,a1]=work(x,xvector,fvector)

What are the ??????? in your code? You had to assign something to them. MATLAB won't just make up something for them out of thin air -- what if it makes up something you didn't want? You have to tell it.

You didn't just push the green run triangle without assigning something for x, xvector, and fvector, did you? Doing that also won't tell MATLAB what to use - they'll be undefined.