# Routine Naming Conventions

For each routine in this chapter, when calling it from the Fortran 77 program you can use the LAPACK name.

LAPACK names have the structure xyyzzz, which is described below.

The initial letter x indicates the data type:

s

  real, single precision

c

  complex, single precision

d

  real, double precision

z

  complex, double precision

The second and third letters yy indicate the matrix type and storage scheme:

bd

  bidiagonal matrix

ge

  general matrix

gb

  general band matrix

hs

  upper Hessenberg matrix

or

  (real) orthogonal matrix

op

  (real) orthogonal matrix (packed storage)

un

  (complex) unitary matrix

up

  (complex) unitary matrix (packed storage)

pt

  symmetric or Hermitian positive-definite tridiagonal matrix

sy

  symmetric matrix

sp

  symmetric matrix (packed storage)

sb

  (real) symmetric band matrix

st

  (real) symmetric tridiagonal matrix

he

  Hermitian matrix

hp

  Hermitian matrix (packed storage)

hb

  (complex) Hermitian band matrix

tr

  triangular or quasi-triangular matrix.

The last three letters zzz indicate the computation performed, for example:

qrf

  form the QR factorization

lqf

  form the LQ factorization.

Thus, the routine sgeqrf forms the QR factorization of general real matrices in single precision; the corresponding routine for complex matrices is cgeqrf.

Names of the LAPACK computational and driver routines for Fortran 95 interface in Intel MKL are the same as Fortran 77 names but without the first letter that indicates the data type. For example, the name of the routine that forms the QR factorization of general real matrices in Fortran 95 interface is geqrf. Handling of different data types is done through defining a specific internal parameter referring to a module block with named constants for single and double precision.

For details on the design of Fortran 95 interface for LAPACK computational and driver routines in Intel MKL and for the general information on how the optional arguments are reconstructed, see Fortran 95 Interface Conventions in “LAPACK Routines: Linear Equations”.

Parent topic: LAPACK Routines: Least Squares and Eigenvalue Problems