Function : undefined function or variable

Hello,

i'm wrote a function fun in a "Vc.m" file and i have to use it in the lsqcurvefit function that i wrote in another file "Identification.m" to find the constants b,m and R as shown below. In my first file i have the message "The function f might be unused" could someone help me please ?

Vc.m

function [Vc] = fun(j,b,m,R)
  Vc(j) = E0-b.*log(j)-R.*j-m.*exp(n.*j);
end

Identification.m

j = [5 30 55 80 105 130 155 180 205 230 255 280 305 330 355 380 405 430 ...
    455 480 505 530 555 580 605 630 655 680 705 730 755 780 805 830 855 880];

V80 = [1.0020 0.9448 0.9229 0.9037 0.8942 0.8810 0.8723 0.8630 0.8548 0.8427 ...
    0.8379 0.8272 0.8152 0.8108 0.8025 0.7921 0.7882 0.7806 0.7770 0.7691 ...
    0.7635 0.7552 0.7473 0.7406 0.7347 0.7300 0.7222 0.7099 0.7065 0.6985 ... 
    0.6932 0.6835 0.6793 0.6679 0.6561 0.6543];

x0 = [0;0];
E0 = 1.5;
n = 8.0E-3;
v80 = lsqcurvefit(@fun,x0,j,V80);

Answer 1

[dpb]

"wrote a function fun in a "Vc.m" file"

but the function

function [Vc] = fun(j,b,m,R)
  Vc(j) = E0-b.*log(j)-R.*j-m.*exp(n.*j);
end

is fun, not VC and so it should be saved in and referred to as fun.m not Vc.m

[ABDALLAH BOINA Safinati-Amir]

Hello,

i'll change it thanks