Undefined operator .^ occurs help!!

I’m doing homework; actually basic class. I just wrote everything on the given material, but I can’t still get the answer. Here’s codes:

xdata = { 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 };
ydata = { 5.17641 4.20461 3.31091 2.60899 2.23541 1.97771 1.88141 1.62821 1.50138 1.51075 1.4085 1.26222 1.09432 1.13202 1.12918 1.10355 1.11867 1.0974 1.08324 1.05687 1.19422 1.22984 1.34516 1.19713 1.25398 1.29885 1.33658 1.31166 1.40332 1.3955 1.37855 1.41491 1.59549 1.56027 1.63925 1.7244 1.74192 1.82049 };
fun = @(p) sum((ydata-(1/3)*(xdata.^2 + (2*(1+p)/xdata)))^2);
pguess = 0.1;
[p,fminres] = fminsearch(fun,pguess)

What is the problem with these codes? Would you help me?

Answer 1

[Stephen23]

"I just wrote everything on the given material"

If that is the case then that material is wrong:

• {} creates a cell array (similar to a list in other languages),
• [] concatentates those numeric scalars into one numeric array:

xdata = [0.15 0.2 ...1.9 1.95 2];
        ^                      ^ Creates a numeric array from numeric scalars!

It seems that your function is also missing a few characters:

fun = @(p) sum((ydata-(1/3)*(xdata.^2 + (2*(1+p)./xdata))).^2);
                                                ^         ^

After which i get:

p =  0.19589
fminres =  0.26543

[KyungDeok Baek]

Thank you for your nice answer!

Answer 2

[KSSV]

xdata = [0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 ];
ydata = [ 5.17641 4.20461 3.31091 2.60899 2.23541 1.97771 1.88141 1.62821 1.50138 1.51075 1.4085 1.26222 1.09432 1.13202 1.12918 1.10355 1.11867 1.0974 1.08324 1.05687 1.19422 1.22984 1.34516 1.19713 1.25398 1.29885 1.33658 1.31166 1.40332 1.3955 1.37855 1.41491 1.59549 1.56027 1.63925 1.7244 1.74192 1.82049 ];
fun = @(p) sum((ydata-(1/3).*(xdata.^2 + (2*(1+p)./xdata))).^2);
pguess = 0.1;
[p,fminres] = fminsearch(fun,pguess)

{} replace by []. {} is a cell. [] is a matrix.