Passing xtra parameter

i do an example provide in matlab on passing xtra parameter. these are the codes:

function y = parameterfun(x,a,b,c)
a = 4; b = 2.1; c = 4;           % Assign parameter values
x0 = [0.5,0.5];
y = (a - b*x(1)^2 + x(1)^4/3)*x(1)^2 + x(1)*x(2) +(-c + c*x(2)^2)*x(2)^2;
f = @(x)parameterfun(x,a,b,c);
[x,fval] = fminunc(f,x0)
end

However, i got an error said that:

??? Input argument "x" is undefined.

Error in ==> parameterfun at 4
y = (a - b*x(1)^2 + x(1)^4/3)*x(1)^2 + x(1)*x(2) +(-c + c*x(2)^2)*x(2)^2;

please help me. I dont know how to fix it. tq

Answer 1

[Geoff]

That doesn't look right. I am guessing you intended to do the following:

function y = parameterfun(x,a,b,c)
  y = (a - b*x(1)^2 + x(1)^4/3)*x(1)^2 + x(1)*x(2) +(-c + c*x(2)^2)*x(2)^2;
end

a = 4; b = 2.1; c = 4;           % Assign parameter values
x0 = [0.5,0.5];
f = @(x)parameterfun(x,a,b,c);
[x,fval] = fminunc(f,x0)

[srycandy]

I get this error, when i use ur suggestion.

??? Error: File: parameterfun.m Line: 5 Column: 1

This statement is not inside any function.

(It follows the END that terminates the definition of the function

"parameterfun".)

[srycandy]

i already get the answer... silly me.. starting line 4 to last line , we have to run it at command prompt.. why it has to be like that?