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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

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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

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

Shantanu K
on 7 Mar 2013

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.

Walter Roberson
on 7 Mar 2013

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"

## 6 Comments

## Walter Roberson (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134721

Your statement y=a*x+b*k+1; is completely overwriting any previous value of the variable "y", including the use of "y" as an array from the previous iteration of the very next line.

## Shantanu K (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134753

Thanks Walter, can you guide me in finding the maximum value of 'y' & corresponding 'a' & 'b' values

## Walter Roberson (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134757

"y" cannot be simultaneously a scalar and an array. You need to use a different name for one of the two. Or just skip the temporary variable and use

## Shantanu K (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134793

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

## Walter Roberson (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134795

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

## Shantanu K (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/66209#comment_134866

Thanks Walter for your help !