minindc#

Purpose#

Returns a column vector containing the index (i.e., row number) of the smallest element in each column of a matrix.

Format#

y = minindc(x)#

Parameters:: x (NxK matrix) – data
Returns:: y (Kx1 matrix) – contains the index of the smallest element in each column of x.

Examples#

// Create random matrix
x = round(rndn(5, 4)*5);

// Find minimum of each column
y = minc(x);

// Find indices of minimum of each column
z = minindc(x);

If x is equal to:

     -5      4     -4      0
     -2      3      4      3
x = -11      5      5      5
      1      2      7      4
     -2      4     -1     -5

then y and z are equal to:

    -11          3
y =   2      z = 4
     -4          1
     -5          5

Remarks#

If x is complex, minindc() uses the complex modulus (abs(x)) to determine the smallest elements.

To find the index of the smallest element in each row, transpose the matrix before applying minindc().

To find the index of the smallest element in a matrix x, use:

colInd = minindc(minc(x));
rowInd = minindc(x[.,colInd]);

If there are two or more “smallest” elements in a column (i.e., two or more elements equal to each other and less than all other elements), then minindc() returns the index of the first one found, which will be the smallest index.