Data Types

All Sun MPI communication routines have a data type argument. These may be primitive data types, such as integers or floating-point numbers, or they may be user-defined, derived data types, which are specified in terms of primitive types.

Derived data types allow users to specify more general, mixed, and noncontiguous communication buffers, such as array sections and structures that contain combinations of primitive data types.

The basic data types that can be specified for the data-type argument correspond to the basic data types of the host language. Values for the data-type argument for Fortran and the corresponding Fortran types are listed in the following table.

Table 2-2 Possible Values for the Data Type Argument for Fortran

MPI Data Type	Fortran Data Type
MPI_INTEGER	INTEGER
MPI_REAL	REAL
MPI_DOUBLE_PRECISION	DOUBLE PRECISION
MPI_COMPLEX	COMPLEX
MPI_LOGICAL	LOGICAL
MPI_CHARACTER	CHARACTER(1)
MPI_DOUBLE_COMPLEX	DOUBLE COMPLEX
MPI_REAL4	REAL*4
MPI_REAL8	REAL*8
MPI_INTEGER2	INTEGER*2
MPI_INTEGER4	INTEGER*4
MPI_BYTE
MPI_PACKED

Values for the data-type argument in C and the corresponding C types are listed in the following table. .

Table 2-3 Possible Values for the Data Type Argument for C

MPI Data Type	C Data Type
MPI_CHAR	signed char
MPI_SHORT	signed short int
MPI_INT	signed int
MPI_LONG	signed long int
MPI_UNSIGNED_CHAR	unsigned char
MPI_UNSIGNED_SHORT	unsigned short int
MPI_UNSIGNED	unsigned int
MPI_UNSIGNED_LONG	unsigned long int
MPI_FLOAT	float
MPI_DOUBLE	double
MPI_LONG_DOUBLE	long double
MPI_LONG_LONG_INT	long long int
MPI_BYTE
MPI_PACKED

The data types MPI_BYTE and MPI_PACKED have no corresponding Fortran or C data types.