Matrix functions

These functions perform matrix operations:


PRODUCT
Matrix product (the same as the operator *+)

LTPRODUCT
Product after transposing left matrix, i.e. L′ *+ R

RTPRODUCT
Product after transposing right matrix, i.e. L *+ R′

QPRODUCT
Quadratic product, i.e. M *+ S *+ M′

QTPRODUCT
Quadratic transposed matrix product, i.e. M′ *+ S *+ M

DETERMINANT
Determinant of a square matrix

INVERSE
Inverse of a square, symmetric or diagonal matrix

GINVERSE
Moore-Penrose generalized inverse

TRANSPOSE
Transpose of a matrix, i.e. M′

TRACE
Trace of a square matrix

CHOLESKI
Choleski decomposition of a matrix

EVALUES
Eigenvalues (as a diagonal matrix)

EVECTORS
Eigenvectors (as a rectangular matrix)

SVALUES
Singular values (as a diagonal matrix)

LSVECTORS
Matrix of left-hand vectors from a singular-value decomposition

RSVECTORS
Matrix of right-hand vectors from a singular-value decomposition

DPRODUCT
Direct product of matrices (synonym KRONECKER)

DSUM
Direct sum of matrices

MCENTRE
Centre matrix so that columns have mean zero and variance one

MEXP
Matrix exponential

MPOWER
Matrix power

MSQRT
Matrix square root

CORRMAT
Correlation matrix derived from a symmetric matrix

SUBMAT
Forms sub-triangles or sub-rectangles

DIAGONAL
Forms a diagonal matrix from a variate, or takes diagonal (or banded diagonal) of a square, symmetric or diagonal matrix

LTRIANGLE
Takes lower triangle of a square matrix (setting upper to zero)

UTRIANGLE
Takes upper triangle of a square matrix (setting lower to zero)

COLSUMS
Sums of columns

COLMEANS
Means of columns

COLNOBSERVATIONS
Numbers of non-missing elements in columns

COLCENTRE
Centres columns by subtracting their means

ROWSUMS
Sums of rows

ROWMEANS
Means of rows

ROWNOBSERVATIONS
Numbers of non-missing elements in rows

ROWCENTRE
Centres rows by subtracting their means

SOLUTION
Solution of simultaneous linear equations

VEC
Stacks columns of a matrix into a single variate

VECH
Stacks columns of the lower triangle of a matrix


These functions generate matrices with particular structures:


IDENTITY
Identity matrix

COL1
Column matrix of 1's

ROW1
Row matrix of 1's

MAT1
Matrix of ones

BASE
Column matrix with n rows, value one in row i and zero elsewhere

MBASE
Matrix with ones at specified positions, and zeros elsewhere

MZERO
Zero matrix

MAT0
Synonym of MZERO


These functions give information about matrices:


NCOLUMNS
Gives the number of columns of a matrix

NROWS
Gives the number of rows of a matrix


These functions form matrices from tables:


TCOLUMN
Converts a one-way table into a column matrix

TDIAGONAL
Converts a one-way table into a diagonal matrix

TMATRIX
Converts a two-way table into a matrix

TROW
Converts a one-way table into a row matrix