optimisation of simple equation

let say a=1:1:10 b=1:1:20 c:1:1:15 and the equation is:

k= (a/b)*cos(c)

and i need to get the value of a b and c when k is min or max, how do you do it?

thx

Answer 1

[Andrei Bobrov]

% determination of all combinations of values of the vectors a,b,c -> [a(:) b(:) c(:)]  

[a b c] = meshgrid(1:10,1:20,1:15 );

% definition of all possible values of 'k'

k = a(:)./b(:).*cos(c(:));

% min and max values of 'k', [i1,i2] - indexes of the min and max values

[v1,i1] = max(k);
[v2,i2] = min(k);

% first row of the 'out' values of the 'a','b' and 'c' when 'k' -max, second - 'k' - min

out = [a(i1) b(i1) c(i1);a(i2) b(i2) c(i2)]

[kevin]

thanks for the answer, but can you write a short sentence which say what each line do?

[kevin]

how would you do the same with four variable? i get

??? Error: File: The_Crane_Design.m Line: 10 Column: 49

Unbalanced or unexpected parenthesis or bracket.

when i try more than 3

[Sven]

"Unbalanced or unexpected parenthesis or bracket" means that the code you have has a small typo... a missing parenthesis or bracket.

[kevin]

i wrote

[a b r t p] = meshgrid(1:0.1:4,1:0.1:4,1.2:0.1:2.2,-20:0.5:80,0:0.5:90);

do you see any error?

[kevin]

i am think i got error for it was because meshgrid only support 3 varibles ie 3d