Element Types

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An element type is a basic type of the language, used to describe a variable which holds a single element or each element of a collection. There are a number of different element types, all sharing the same communication behaviour, which allow the programmer to describe a wide variety of data. The size (in bytes) that each element type requires for storage is implementation specific, however according to the C99 standard a character is guaranteed to be 1 byte.

Type	Semantics
Int	A whole number
Double	A double precision number
Float	A floating point number
Bool	A true or false value
Char	A character
String	A string of characters
File	A file handle

For communication, these element types have specific behaviours when used within an SPMD style of programming. However, if the programmer issues an assignment which would require communication in a MPMD style (e.g. in a par loop) then the compiler will report this as an error (as this operation is not allowed due to the possibility of accidental deadlock.) For the assignment a:=b

a	b	Result
multiple	multiple	local assignment
single[x]	multiple	local on process x only
multiple	single	MPI Broadcast
single[x]	single[x]	Where x==x local
single[x]	single[q]	Where x != q, P2P communication

Last Modified: August 2008