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The DEFAULT clause lets you specify the default attribute for variables in the lexical extent of theparallel region. Individual clauses specifying PRIVATE, SHARED, etc. status override the declaredDEFAULT. Specifying DEFAULT(NONE) declares that there is no implicit default, and in thiscase, each variable in the parallel region must be explicitly listed with an attribute of PRIVATE,SHARED, FIRSTPRIVATE, LASTPRIVATE, or REDUCTION.Variables that appear in the list of a FIRSTPRIVATE clause are subject to the same semantics asPRIVATE variables, but in addition, are initialized from the original object existing prior toentering the parallel region. Variables that appear in the list of a REDUCTION clause must beSHARED. A private copy of each variable in list is created for each thread as if the PRIVATEclause had been specified. Each private copy is initialized according to the operator as specified inthe following table:Table 8-1: Initialization of REDUCTION VariablesOperator / IntrinsicInitialization+ 0* 1− 0.AND..TRUE..OR..FALSE..EQV..TRUE..NEQV..FALSE.MAXsmallest representable numberMINlargest representable numberIANDall bits onIOR 0IEOR 0At the end of the parallel region, a reduction is performed on the instances of variables appearingin list using operator or intrinsic as specified in the REDUCTION clause. The initial value of eachREDUCTION variable is included in the reduction operation. If the {operator |intrinsic}: portion of the REDUCTION clause is omitted, the default reduction operator is“+” (addition).The COPYIN clause applies only to THREADPRIVATE common blocks. In the presence of theCOPYIN clause, data from the master thread’s copy of the common block is copied to thethreadprivate copies upon entry to the parallel region.290 Chapter 8