Magnitude, row and column in a Matrix

Good Morning.

I have a matrix A

A = [87.97 87.97 17.97

95.22 87.96 91.26

75.50 75.50 75.50

78.13 64.89 78.90];

What instructions should I do to get

Minimum value per column

The line and column of that value

The result would be:

magnitude 75.50 64.89 17.97

row 3 4 1

column 1 2 3

Greetings and thanks

Answer 1

[Star Strider]

Try this:

A = [87.97   87.97    17.97
    95.22    87.96    91.26
    75.50    75.50    75.50
    78.13   64.89   78.90];

[MaxA,MaxRow] = max(A)
[MinA,MinRow] = min(A)

producing:

MaxA =
   95.2200   87.9700   91.2600

MaxRow =
     2     1     2

MinA =
   75.5000   64.8900   17.9700

MinRow =
     3     4     1

[Ricardo Gutierrez]

Hi.

Thanks for your help

Now I need to know the column number where this is the minimum value. How do I do that?

The real matrix is 20 X 18

[Star Strider]

Find both the row and column of the minimum with the find function:

[RowMin,ColMin] = find(A == min(A(:)))

producing:

RowMin =
     1

ColMin =
     3

The ‘(:)’ subscript convention forces a column vector, so ‘min(A(:))’ will return the minimum of that column, or the minimum for all of ‘A’. Then all find needs to do is return the row and column indices to it.

To return only the column, the find call becomes:

     [~,ColMin] = find(A == min(A(:)))

[Ricardo Gutierrez]

Hi

I only get only the minimum of the columns and I would like to know the minimum of each column.

__________________________________________

clc; clear; close all; format short;

A=[ 87.97 87.97 17.97

95.22 87.96 91.26

75.50 75.50 75.50

78.13 64.89 78.90];

[MinA,MinRow] = min(A)

[~,ColMin] = find(A == min(A(:)))

____________Command Window___________________________

MinA =

75.5000 64.8900 17.9700

MinRow =

3 4 1

ColMin =

3

[Star Strider]

As always, my pleasure.

The minimum of each column is in the ‘minA’ result:

MinA =
   75.5000   64.8900   17.9700

The same is true for the code for the maximum for each column, returned in ‘maxA’.

The maximum row and column for ‘A’ is:

   [RowMax,ColMax] = find(A == max(A(:)))

[Ricardo Gutierrez]

This is the code I have, with your suggestions.

______________________________________________

clc; clear; close all; format short;

A=[ 87.97 87.97 17.97

95.22 87.96 91.26

75.50 75.50 75.50

78.13 64.89 78.90];

[MinA,MinRow] = min(A)

[RowMin,ColMin] = find(A == min(A(:)))

__________________________________________________

This is the results show in the Command Window

______________________________________________

MinA =

75.5000 64.8900 17.9700

MinRow =

3 4 1

RowMin =

1

ColMin =

3

ColMin =

3

>>

___________________________________________

As we see it does not show me the columns.

It shows me only one

Already the minimum values and the rows are resolved, only the columns are missing.

Thanks for your help

[Star Strider]

It actually shows everything you want it to show.

Answer 2

[Walter Roberson]

Use the two output form of min(). The second output will be the appropriate row numbers.

[Ricardo Gutierrez]

Hi.

Thanks for your help.

With your suggestion I would know the magnitude of the minimum value and the row number it is. Now I need to know in which column this value is.

The actual matrix is 20 X 18

Greetings and thanks

[Walter Roberson]

The column number is 1:number of columns

[Ricardo Gutierrez]

Thanks