you are designing a rectangular page to contain 60 inch^2 of printing with a 4-inch marging at the top bottom and a 2-inch margin at each side.what overall dimensions will minimize the amount of paper used?

%Solving problem 2
fprintf('Code for problem 2 \n')
area = 60;
syms 1 b;
1 == (60/(b-4)) + 8;
A = 1 * b;
A = diff(A, b) == 0;
[b1] = solve(A);
[11] = [(60/(b1(1)-4)) + 8, (60/(b1(2)-4)) + 8];
fprintf('Dimensions of page for minimum area is :\n')
if (11(1)<0)
    fprintf('Length : %f\n', 11(2))
    fprintf('Breadth : %f\n', b1(2))
elseif(11(1)>0 && 11(2)>0)
    fprintf('Lenght1 : %f\n', 11(1))
    fprintf('Breadth1 : %f\n', b1(1))
    fprintf('Length2 : %f\n',11(2))
    fprintf('Breadth2 : %f\n',b1(2)
else
    fprintf('Length : %f\n', 11(1))
    fprintf('Breadth: %f\n', b1(1))
end



and i am getting errors be like
'invalid eprssion when calling a fuction or indexing a variable,use parentheses otherwise,check for mismatched delimiters'

Answer 1

[Guillaume]

While this is valid matlab:

1 == (60/(b-4)) + 8;

it doesn't do much. Without the semicolon at the end, it would just display whether the comparison is true or false. With the semicolon suppressing output, it simply doesn't do anything.

This, on the other hand:

[11] = [(60/(b1(1)-4)) + 8, (60/(b1(2)-4)) + 8];

attempts to assign the result of an expression to 11, which is meaningless, and indeed will result in an error. The expression on the left side of an = must be a variable (indexed or not).