returning the input value with maximum output

i want to get the input that maximize the output. how to get this value?

here is the programe code.

a=[ 1 2 3];
b=[7 4 2];

y=2.*a+5.*b; % the output should be y = [37 24 16]

ymax=max(y); %37 where the value a=1,b=7

so, what function can i use to return the value a=1 and b=7?

Answer 1

[David Sanchez]

There are several choices to find minimum/maximum values. You can take a look at the built-in function fmincon for example. In your case, if the data you present is the data, you can do something like this:

% find the maximum value in the output array:
[y_max max_indes] = max(y);
a_max = a(max_index); % get the corresponding value from the _a_ array
b_max = b(max_index); % get the corresponding value from the _b_ array

[azie]

thats give me an error said " undefined function 'max_index' ".

do i need to define the max_index?

[Iain]

Correct his typo: :P

 [y_max max_index] = max(y);