MATLAB Answers

Shantanu K
0

How to find maximum value for 3 iterative variables.

Asked by Shantanu K
on 7 Mar 2013

In this i have to do following operation mentioned:

Here value of a,b,z are changing continuously. For every value program will calculate value of 'y'.

It will become three dimensional array.

For entire these iterations i have to find out maximum value of 'y' and corresponding value of 'a' & 'b'.

I am facing one more problem, when i formulated array it was showing lot more zeros.

for p=1:6
      a=2*p;
      for q=1:6
          b=5*q;
            for z=1:100
                 k=z*z;
                 x=k*4+1;
                 y=a*x+b*k+1;
                 y(p,q,z)=y;
            end
        end
    end

  6 Comments

p=0;
q=0;
z=0;
for p=1:6
      for q=1:6
          for z=1:100
              a=2*p;
              b=5*q;
               k=z*z;
               x=k*4+1;
               y(p,q,z)=a*x+b*k+1;
          end
      end
  end

How to find maximum value of 'y' and get corresponding value of 'p' and 'q'?

Do you want the 'a' and 'b' (as you wrote the first time) or the 'p' and 'q' (as you write now) ?

Thanks Walter for your help !

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2 Answers

Answer by Andrei Bobrov
on 7 Mar 2013
Edited by Andrei Bobrov
on 7 Mar 2013
 Accepted answer

max1 = [-inf 0 0 0];
for p=1:6
    for q=1:6
        for z=1:100
            a=2*p;
            b=5*q;
            k=z*z;
            x=k*4+1;
            k1 = a*x+b*k+1; 
            y(p,q,z) = k1;
            if k1 > max1(1), max1 = [k1,p,q,z]; end 
        end
    end
end

  2 Comments

Re-using the variable "k" could be confusing to me.

Oh! Typo, thank you, Walter!

Corrected.


Answer by Walter Roberson
on 7 Mar 2013

Before loop:

maxy = -inf;
a_at_max = -inf;
b_at_max = -inf;

then inside the loop, where you assign into y, test to see if the new value is greater than maxy, and if it is, record the a and b values

  2 Comments

I am not able to understand it sir, can you please elaborate?

then inside the loop, where you assign into y, test to see if the new value is greater than maxy, and if it is, record the a and b values This part i am not able to convert to program.

if y(p,q,z) > maxy
  %then update your record of which "a" and "b" values led to this maximum
end

Oh yes and remember to update maxy with the new maximum as well.

Hint: "update" means "do an assignment to"


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