Naming Conventions

      IMPLICIT COMPLEX (C)

      IMPLICIT DOUBLE PRECISION (D)

      IMPLICIT INTEGER (I-N)

      IMPLICIT DOUBLE COMPLEX (Z)

The first letter of a subroutine name identifies the type of the result. The second and third letters identify the form of the output matrix and its mode of storage in an array. The forms are shown below:

CH	Cholesky-factored
GB	general in banded storage
GE	general
GT	general tridiagonal
HI	Hermitian
HP	Hermitian in packed storage
PB	symmetric positive definite in banded storage
PO	symmetric positive definite
PP	symmetric positive definite in packed storage
PT	symmetric positive definite tridiagonal
QR	QR-factored
SI	symmetric
SP	symmetric in packed storage
TR	triangular

When the second and third letters indicate the type of matrix and its storage mode, the fourth and fifth letters indicate the operation that will be performed. The fourth and fifth letters mean different things for different subroutines, so you must read the description of the subroutine in order to find out exactly what it does. For example, DTRCO estimates the condition of a triangular matrix. DGECO estimates the condition of a general matrix and also determines the LU factorization. The operations are shown below:

CO	Estimate the condition number; sometimes also determine the LU or Cholesky factorization
DC	Decomposition
DD	Downdate a Cholesky factorization
DI	Compute the determinant of a matrix; sometimes also determine the inverse and inertia of a matrix
EX	Permute and update a Cholesky factorization
FA	Factor
SL	Solve a system of linear equations, usually after the matrix has been factored by a subroutine whose name ends in CO or FA
UD	Update a Cholesky factorization

A^-1 denotes the inverse of the square matrix stored in the array A. Whenever the symbol A^-1 appears it is assumed that the numerical inverse of the matrix stored in the array A exists. A^T denotes the transpose of an array A and A^H denotes the conjugate transpose of A for a complex matrix A.