Intel(R) - Computational and Systems Biology at MIT

3 Intel® Math Kernel Library User’s GuideConceptILP64 interface is provided for the following two reasons:• To support huge data arrays, that is, arrays with more than 2 billion elements• To enable compiling your Fortran code with the -i8 compiler option.The Intel® Fortran Compiler supports the -i8 option for changing behavior of the INTEGERtype. By default the standard INTEGER type is 4-byte. The -i8 option makes the compilertreat INTEGER constants, variables, function and subroutine parameters as 8-byte.The ILP64 binary interface uses 8-byte integers for function parameters that define arraysizes, indices, strides, etc. At the language level, that is, in the *.f90 and *.fi fileslocated in the Intel MKL include directory, such parameters are declared as INTEGER.To bind your Fortran code with the ILP64 interface, you must compile your code with the-i8 compiler option. And vice-versa, if your code is compiled with -i8, you can bind it onlywith the ILP64 interface, as the LP64 binary interface requires the INTEGER type to be4-byte.Note that some Intel MKL functions and subroutines have scalar or array parameters oftype INTEGER*4 or INTEGER(KIND=4), which are always 4-byte, regardless of whether thecode is compiled with the -i8 option.For the languages of C and C++, Intel MKL provides the MKL_INT type as a counterpart ofthe INTEGER type for Fortran. MKL_INT is a macro defined as the standard C/C++ type intby default. However, if the MKL_ILP64 macro is defined for the code compilation, MKL_INTis defined as a 64-bit integer type. To define the MKL_ILP64 macro, you may call thecompiler with the -DMKL_ILP64 command-line option.Intel MKL also defines the type MKL_LONG for maintaining ILP64 interface in the specificcase of FFT interface for C/C++. The MKL_LONG macro is defined as the standard C/C++type long by default; and if the MKL_ILP64 macro is defined for the code compilation,MKL_LONG is defined as a 64-bit integer type.NOTE. The type int is 32-bit for the Intel® C++ compiler, as well as formost of modern C/C++ compilers. The type long is 32- or 64-bit for theIntel® C++ and compatible compilers, depending on the particular OS.In the Intel MKL interface for the C or C++ languages, that is, in the *.h header fileslocated in the Intel MKL include directory, such function parameters as array sizes, indices,strides, etc. are declared as MKL_INT.The FFT interface for C/C++ is the specific case. The header file mkl_dfti.h uses theMKL_LONG type for both explicit and implicit parameters of the interface functions.Specifically, type of the explicit parameter dimension of the function3-6