How to find maximum value for 3 iterative variables.

2013 3 7
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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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Walter Roberson
Walter Roberson 2013-3-7
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
Shantanu K 2013-3-7
编辑：Shantanu K 2013-3-7
Thanks Walter, can you guide me in finding the maximum value of 'y' & corresponding 'a' & 'b' values
Walter Roberson
Walter Roberson 2013-3-7
"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
y(p,q,z) = a*x + b*k + 1;
Shantanu K
Shantanu K 2013-3-7
编辑：Walter Roberson 2013-3-7
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'?
Walter Roberson
Walter Roberson 2013-3-7
Do you want the 'a' and 'b' (as you wrote the first time) or the 'p' and 'q' (as you write now) ?
Shantanu K
Shantanu K 2013-3-7
Thanks Walter for your help !

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 采纳的回答

Andrei Bobrov
Andrei Bobrov 2013-3-7
编辑：Andrei Bobrov 2013-3-7

0 个投票

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

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Walter Roberson
Walter Roberson 2013-3-7
Re-using the variable "k" could be confusing to me.
Andrei Bobrov
Andrei Bobrov 2013-3-7
Oh! Typo, thank you, Walter!
Corrected.

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更多回答（1 个）

Walter Roberson
Walter Roberson 2013-3-7

0 个投票

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

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Shantanu K
Shantanu K 2013-3-7
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
Walter Roberson 2013-3-7
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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