Purpose
The omp sections directive distributes work among
threads bound to a defined parallel region.
Syntax

.-,------.
V |
>>-#--pragma--omp sections----clause-+-------------------------><
Parameters
clause is any of the following:
- private (list)
- Declares the scope of the data variables in list to be private to each thread. Data variables in list are separated by commas.
- firstprivate (list)
- Declares the scope of the data variables in list to be private to each thread. Each new private object is initialized
as if there was an implied declaration within the statement block. Data variables
in list are separated by commas.
- lastprivate (list)
- Declares the scope of the data variables in list to be private to each thread. The final value of each variable in list, if assigned, will be the value assigned to that
variable in the last section. Variables not assigned
a value will have an indeterminate value. Data variables in list are separated by commas.
- reduction (operator: list)
- Performs a reduction on all scalar variables in list using the specified operator. Reduction
variables in list are separated by commas.
A private
copy of each variable in list is created for each
thread. At the end of the statement block, the final values of all private
copies of the reduction variable are combined in a manner appropriate to the
operator, and the result is placed back into the original value of the shared
reduction variable.
Variables specified in the
reduction clause:
- must be of a type appropriate to the operator.
- must be shared in the enclosing context.
- must not be const-qualified.
- must not have pointer type.
- nowait
- Use this clause to avoid the implied barrier at
the end of the sections directive. This is useful if
you have multiple independent work-sharing sections within a given parallel
region. Only one nowait clause can appear on a given sections directive.
Usage
The omp section directive is optional for the first
program code segment inside the omp sections directive.
Following segments must be preceded by an omp section directive.
All omp section directives must appear within the lexical
construct of the program source code segment associated with the omp sections directive.
When program execution reaches a omp sections directive,
program segments defined by the following omp section directive
are distributed for parallel execution among available threads. A barrier
is implicitly defined at the end of the larger program region associated with
the omp sections directive unless the nowait clause is specified.