Error using min MIN with two matrices to compare and a working dimension is not supported.

The code gives me the following error: using min MIN with two matrices to compare and a working dimension is not supported.

The corresponding line in the code:

yp(2) = min(e*f*y(1)/(a+y(1)),(y(3)*f*y(1)/(theta*(a+y(1)))),e*f*theta/y(3))*y(2)-d*y(2);

Could you please help me to fix it?

Answer 1

[Walter Roberson]

Bracket count. Each number indicates the nesting level "after" the bracket above it

        yp(2) = min(e*f*y(1)/(a+y(1)),(y(3)*f*y(1)/(theta*(a+y(1)))),e*f*theta/y(3))*y(2)-d*y(2);
          1 0      1     2 1 2   3 21,2 3 2    3 2 3      4   5 4321,           2 10  1 0    1 0

notice there are two commas inside the min() level, so you are invoking min() with three arguments. min() has two different syntaxes:

min(ARRAY,ARRAY)
min(ARRAY,[],DIMENSION)

there is no syntax for

min(ARRAY,ARRAY,DIMENSION)

and there is no syntax for

min(ARRAY,ARRAY,ARRAY)

If you need to take the min() amongst three arrays, use

min(min(ARRAY,ARRAY),ARRAY)

or

D = ndims(ARRAY) + 1;
min(cat(D,ARRAY,ARRAY,ARRAY),D)

[LALE ASIK]

Thank you so much for your help Walter. I have one more question. Can I also use the following form min([Array; Array; Array])?

[Walter Roberson]

When you use min(A, B) then it proceeds element by element giving you a result the same size as the original with the pairwise minimum.

When you min(A) which is the same case as min([A;B;C]) then you take the minimum along each column giving you a result that has one row and the same number of columns as the original. Not the same.

[LALE ASIK]

Thank you so much for your clarification.