‘optfun’ is function name taking input arguments ‘pair’. Return value of the function is stored in F.
X is assigned with first value of pair. Y is assigned with second value of pair.
Now F has two values, where first value is 3*y+.001*y*exp(x)-4*x and second value are x^2+y^2-25.
At the end F is returned. You can call the function by ‘optfun’ (pair) where defining the pair before calling.
pair = [1 2];
function F = optfun(pair)
x = pair(1);
y = pair(2);
F = [3*y+.001*y*exp(x)-4*x, x^2+y^2-25];