How to loop the constant in a function?

I'm currently stuck on this most likely rather simple problem, but for some reason I can't get it to work. What I want to do is simply to solve the function f(x,k) for a grid of different k:s. As a very simple example, I'd want to solve

y=(x^2)+k for k=1:1:5

with some kind of for-loop, where the answer thus becomes a vector with 5 different answers. My main track has been to loop the command where I ask Matlab to solve the function, i.e. running a script like

for k=1:1:5

X = fminsearch(@ericr,-2,2)

end

where the function looks like

function [ y ] = ericr(x,k)

y=x^2 + k

end

MATLAB does not like this approach at all, and any help if therefore greatly appreciated!

Best regards,

Eric

Answer 1

[Eric]

It turned out it was as easy as making sure "k" is a global variable (I forgot to write "global k" in both the script and the function file).

Answer 2

[Jos (10584)]

What do you exactly mean by " solve the function "? Do you mean that you have a set of points (X,Y), and you want to fit the function

y = A*(X^2)+k

through it by looking for the value of A that minimises the distances between y and Y, given a specific value of k?

[Eric]

Sorry; that was a bit of a sloppy notation on my part. What I meant by "solve" was to minimize y, i.e. for which x (given the k) do I find a local minimum?

[Jos (10584)]

that would be at x = 0 for every k ... No need for matlab at all ;-)

Answer 3

[Youssef Khmou]

Eric, use anonymous functions better,

Here is your example ( its obvious that k is the y solution):

 N=10;
 for k=1:N
    f=@(x) (x.^2)+k;

    [a,b]=fminsearch(f,rand);
    X(k,1)=a;
    X(k,2)=b;
 end