Algorithm Update
This section lists all the algorithms that can handle execution policy parameter. It further looks at the usage of the Run and Measure function.
We'll cover the following
Execution Policy Parameter
The execution policy parameter was added to most of the existing algorithms.
Here’s the list:
adjacent_difference |
inplace_merge |
replace_copy |
adjacent_find |
is_heap |
replace_copy_if |
all_of |
is_heap_until |
replace_if |
any_of |
is_partitioned |
reverse |
copy |
is_sorted |
reverse_copy |
copy_if |
is_sorted |
rotate |
copy_n |
is_sorted_until |
rotate_copy |
count |
lexicographical_compare |
search |
count_if |
max_element |
search_n |
equal |
merge |
set_difference |
exclusive_scan |
min_element |
set_intersection |
fill |
minmax_element |
set_symmetric_difference |
fill_n |
mismatch |
set_union |
find |
move |
sort |
find_end |
none_of |
stable_partition |
find_first_of |
nth_element |
stable_sort |
find_if |
partial_sort |
swap_ranges |
find_if_not |
partial_sort_copy |
transform |
for_each |
partition |
transform_exclusive_scan |
for_each_n |
partition_copy |
transform_inclusive_scan |
generate |
remove |
transform_reduce |
generate_n |
remove_copy |
uninitialized_copy |
includes |
remove_copy_if |
uninitialized_copy_n |
inclusive_scan |
remove_if |
uninitialized_fill |
inner_product |
replace |
uninitialized_fill_n |
unique |
unique_copy |
New Algorithms
To fully support new parallel execution patterns The Standard Library was also equipped with a set of new algorithms:
Algorithm | Description |
---|---|
for_each |
similar to for_each except returns void |
for_each_n |
applies a function object to the first n elements of a sequence |
reduce |
similar to accumulate , except out of order execution to allow parallelism |
transform_reduce |
transforms the input elements using a unary operation, then reduces the output out of order |
exclusive_scan |
parallel version of partial_sum , excludes the i-th input element from the i-th sum, out of order execution to allow parallelism |
inclusive_scan |
parallel version of partial_sum , includes the i-th input element in the i-th sum, out of order execution to allow parallelism |
transform_exclusive_scan |
applies a functor, then calculates exclusive scan |
transform_inclusive_scan |
applies a functor, then calculates inclusive scan |
The new algorithms form three groups: for_each
, reduce
and then scan
, plus their alternatives.
With reduce
and scan
you also get “fused” versions like transform_reduce
.
These compositions should give you much better performance than using two separate steps - because the cost of parallel execution setup is smaller and also you have less one loop traversals.
The new algorithms also provide overloads without the execution policy parameter so that you can use them in a standard serial version.
In the next lesson, you’ll find a description of each group.
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