how to find max value of a function with a for loop

Hi,

I have a vector x and a vector y with both vectors having 10 elements and I have a function which uses a for loop to give a value to a variable e with each respective value of y and x. The for loop works as such;

for i=1:length(x)

e=y(i)-(m*x(i)+b)

end

and I want to display only the max value of e in the command window and the respective x and y elements that correspond to it. How would I do this?

Answer 1

[James Tursa]

Make e a vector. E.g.,

for i=1:length(x)
    e(i) = y(i) - (m*x(i)-b);  % <-- Are you sure that isn't supposed to be (m*x(i) + b) with a plus?
end

Then use the max function:

[E,Z] = max(abs(e));

E will contain the max (abs), and Z will contain the index of the max, so

e(Z) is the max (abs)

x(Z) is the x of the max

y(Z) is the y of the max

[Abdur Rahman Hashmi]

Thanks! Yeah i wrote it down wrong, it is with a plus. I'll edit my question so it will show up correctly.

Answer 2

[Sindar]

Loop isn't necessary unless you can't store the data in memory:

e=y-(m*x-b);
[e_max,idx] = max(e);
x_max = x(idx);
y_max = y(idx);