Making a loop with 3 variables

Hello,

I'm new to matlab and need help making a code for obtaining an optimize value. Lets say I have y=a^2-8*b+C*2/ab for example and I have to obtain y<x where a=1:5, b=30:100 and c=20:30.

So I first use an initial value for a, b, and c, then if y<x is not met it will recalculate with a different value a,b,c until y<x is satisfied. Basically making a loop.

Is it possible to code this?

Thanks in advance

Answer 1

[Ahmed raafat]

why loop??? use this beautiful method

   a=1:5;
   b=30:100;
   c=20:30;
   [a,b,c]=meshgrid(a,b,c);
   y=a.^2+8*b+2.*c./a./b;

This will produce matrix with size(71,5,11)

you can get the minimum result in the next line

x=min(min(min(y)));

[Ahmed raafat]

if you want all values of y<x

   [r1,r2,r3]=find(y<x);

[Walter Roberson]

Close, but to get the proper indices you should use

idx = find(y<x);
[r1, r2, r3] = ind2sub(size(y), idx);

The reason for this is that when you use three outputs to find(), the third output is the value at the location, which is especially useful for sparse arrays.

[Zebedee Mojuntin]

Cheers guys!

[JohnB]

Hi, and where can you get the values of a_min, b_min and c_min to obtain the minimum ?

Regards