Utility

Provides additional utility functionality used by multiple modules. More...

Collaboration diagram for Utility:

Modules
	Bloom Filter
	Provides seqan3:bloom_filter.
	Builtin Character Operations
	Provides various operations on character types.
	Concept
	Provides various general purpose concepts.
	Container
	Provides various general purpose container and concepts.
	Range
	The range module provides general purpose range concepts.
	Tuple
	Additional helper utilities for "tuple" types like std::tuple, std::pair, seqan3::pod_tuple that are not specific to a SeqAn module.
	Type List
	Provides seqan3::type_list and metaprogramming utilities for working on type lists.
	Type Pack
	Provides metaprogramming utilities for working on template parameter packs.
	Type Traits
	Provides various type traits and their shortcuts.
	Views
	Views are "lazy range combinators" that offer modified views onto other ranges.

Functions
template<typename base_t , std::unsigned_integral exp_t> requires (std::same_as<base_t, uint64_t> || std::same_as<base_t, int64_t>)
base_t	seqan3::pow (base_t base, exp_t exp)
	Computes the value of base raised to the power exp.

Detailed Description

Provides additional utility functionality used by multiple modules.

The utility module contains concepts, functions, traits and classes that are independent of the remaining modules in SeqAn. These implementations are considered external functionality, i.e. they could have been outsourced into their own libraries.

The utility module has no dependency to any other module except the Core module.

Function Documentation

pow()

template<typename base_t , std::unsigned_integral exp_t>
requires (std::same_as<base_t, uint64_t> || std::same_as<base_t, int64_t>)

base_t seqan3::pow	(	base_t	base,
		exp_t	exp
	)

Computes the value of base raised to the power exp.

Parameters

[in]	base	The base to compute the power for.
[in]	exp	The power to raise base to.

Returns

\( base^{exp} \).

Exceptions

std::overflow_error	if an overflow occurs (Only in Debug build).
std::underflow_error	if an underflow occurs (Only in Debug build).

See also

https://en.cppreference.com/w/cpp/numeric/math/pow

The difference to std::pow is that the powers of an integer base are computed exact (without precision loss due to promoting to double) iff exp_t models std::unsigned_integral and

• base_t models std::unsigned_integral (returns uint64_t)
• base_t models std::integral, but not std::unsigned_integral (returns int64_t)

In all other cases the return value and type is equivalent to that of std::pow.

Example

// SPDX-FileCopyrightText: 2006-2024 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2024 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: CC0-1.0
 
#include <seqan3/core/debug_stream.hpp>
#include <seqan3/utility/math.hpp>
 
int main()
{
    // Uses specialisation for signed integers.
    seqan3::debug_stream << seqan3::pow(2, 3u) << '\n';  // Prints 8
    seqan3::debug_stream << seqan3::pow(-2, 3u) << '\n'; // Prints -8
 
    // Uses specialisation for unsigned integers.
    seqan3::debug_stream << seqan3::pow(2u, 3u) << '\n'; // Prints 8
 
    // Uses `std::pow`.
    seqan3::debug_stream << seqan3::pow(2, 3) << '\n';   // Prints 8
    seqan3::debug_stream << seqan3::pow(2u, 3) << '\n';  // Prints 8
    seqan3::debug_stream << seqan3::pow(2.0, 3) << '\n'; // Prints 8
 
    // 5^25 should be 298023223876953125.
    seqan3::debug_stream << seqan3::pow(5u, 25u) << '\n';                     // Prints 298023223876953125
    seqan3::debug_stream << static_cast<uint64_t>(std::pow(5u, 25u)) << '\n'; // Prints 298023223876953152 (wrong!)
}