How do I create a function without getting this Error: Function definitions are not permitted in this context?

I'm trying to create this function, and I am getting an error. I don't know what I am doing wrong...

 >> function [y] = myfunc( x, y, z )
y = -9*x - 10*y+ z*(-log(100-x-y)-log(x)-log(y)-log(50-x+y)); 

 end
 function [y] = myfunc( x, y, z )
 ↑
Error: Function definitions are not permitted in this context.

Answer 1

[Stephen23]

Only anonymous functions may be defined in the command window:

 >> fun = @(x,y,z)-9*x - 10*y+ z*(-log(100-x-y)-log(x)-log(y)-log(50-x+y));
 >> fun(1,2,3)
 ans =
          -56.599051375363

Other function types (those defined using the keyword function) must be defined in an Mfile.

Answer 2

[KSSV]

I guess you have copied this under some already existing code. Copy this in fresh m file and save.