# Intel® MKL Fortran 95 Interfaces for LAPACK Routines vs. Netlib Implementation

The following list presents general digressions of the Intel MKL LAPACK95 implementation from the Netlib analog:

- Intelc MKL Fortran 95 interfaces are provided for pure procedures.
- Names of interfaces do not contain the LA_ prefix.
- An optional array argument always has the target attribute.
- Functionality of the Intel MKL LAPACK95 wrapper is close to the Fortran 77 original implementation in the getrf, gbtrf, and potrf interfaces.
- If jobz argument value specifies presence or absence of z argument, then z is always declared as optional and jobz is restored depending on whether z is present or not. It is not always so in the Netlib version (see “Modified Netlib Interfaces” in Specific Features of Fortran 95 Interfaces for LAPACK Routines).
- To avoid double error checking, processing of the info argument is limited to checking of the allocated memory and disarranging of optional arguments.
- If an argument that is present in the list of arguments completely defines another argument, the latter is always declared as optional.

You can transform an application that uses the Netlib LAPACK interfaces to ensure its work with the Intel MKL interfaces providing that:

1. The application is correct, that is, unambiguous, compiler-independent, and contains no errors.
2. Each routine name denotes only one specific routine. If any routine name in the application coincides with a name of the original Netlib routine (for example, after removing the LA_ prefix) but denotes a routine different from the Netlib original routine, this name should be modified through context name replacement.

You should transform your application in the following cases (see Specific Features of Fortran 95 Interfaces for LAPACK Routines for specific differences of individual interfaces):

- When using the Netlib routines that differ from the Intel MKL routines only by the LA_ prefix or in the array attribute target. The only transformation required in this case is context name replacement. See “Interfaces Identical to Netlib” for details.

- When using Netlib routines that differ from the Intel MKL routines by the LA_ prefix, the target array attribute, and the names of formal arguments. In the case of positional passing of arguments, no additional transformation except context name replacement is required. In the case of the keywords passing of arguments, in addition to the context name replacement the names of mismatching keywords should also be modified. See “Interfaces with Replaced Argument Names” for details.

- When using the Netlib routines that differ from the respective Intel MKL routines by the LA_ prefix, the target array attribute, sequence of the arguments, arguments missing in Intel MKL but present in Netlib and, vice versa, present in Intel MKL but missing in Netlib. Remove the differences in the sequence and range of the arguments in process of all the transformations when you use the Netlib routines specified by this bullet and the preceding bullet. See “Modified Netlib Interfaces” for details.

- When using the getrf, gbtrf, and potrf interfaces, that is, new functionality implemented in Intel MKL but unavailable in the Netlib source. To override the differences, build the desired functionality explicitly with the Intel MKL means or create a new subroutine with the new functionality, using specific MKL interfaces corresponding to LAPACK 77 routines. You can call the LAPACK 77 routines directly but using the new Intel MKL interfaces is preferable. See “Interfaces Absent From Netlib” and “Interfaces of New Functionality” for details.
  Note that if the transformed application calls getrf, gbtrf or potrf without controlling arguments rcond and norm, just context name replacement is enough in modifying the calls into the Intel MKL interfaces, as described in the first bullet above. The Netlib functionality is preserved in such cases.

- When using the Netlib auxiliary routines. In this case, call a corresponding subroutine directly, using the MKL LAPACK 77 interfaces.

Transform your application as follows:

1. Make sure conditions a. and b. are met.
2. Select Netlib LAPACK 95 calls. For each call do the following:
   - Select the type of digression and do the required transformations.
   - Revise results to eliminate unneeded code or data, which may appear after several identical calls.
3. Make sure the transformations are correct and complete.

Parent topic: Fortran 95 Interface Conventions