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 explained 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:

- bb
bidiagonal-block matrix

- 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 the Fortran 95 interface in Intel MKL are the same as the 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 the 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 the 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 the Fortran 95 Interface Conventions in "LAPACK Routines: Linear Equations".