KMINIMA specified number of minima
For vectors, KMINIMA(X,K) is the vector of K smallest elements in X.
For matrices, Y = KMINIMA(X,K) is a matrix with K rows; Y(i,:)
contains the i-th minimum element from each column. For N-D arrays,
KMINIMA(X,K) operates along the first non-singleton dimension.

[Y,I] = KMINIMA(X,K) returns the indices of the minima in vector I.

[Y,I] = KMINIMA(X,K,DIM) operates along
the dimension DIM.

When complex, the magnitude ABS(X) is considered when computing the
minima, and the angle ANGLE(X) is ignored. NaN's are also ignored .