std::valarray

 

C++

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Technical Specifications

 

Numerics library

Common mathematical functions

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accumulate

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adjacent_difference

partial_sum

 

std::valarray

Member functions
valarray::valarray valarray::~valarray valarray::operator= valarray::operator[] valarray::swap valarray::size valarray::resize valarray::sum valarray::min valarray::max valarray::shift valarray::cshift valarray::apply	valarray::operator+valarray::operator-valarray::operator~valarray::operator! valarray::operator+=valarray::operator-=valarray::operator*=valarray::operator/=valarray::operator%=valarray::operator&=valarray::operator|=valarray::operator^=valarray::operator<<=valarray::operator>>=
Non-member functions
swap (C++11) begin (C++11) end (C++11) abs exp log log10 pow sqrt sin cos tan asin acos atan atan2 sinh cosh tanh	operator*operator/operator%operator+operator-operator^operator&operator|operator<<operator>>operator&&operator|| operator==operator!=operator<operator>operator<=operator>=
Helper classes
slice_array gslice_array indirect_array	slice gslice mask_array

 

Defined in header <valarray>
template< class T > class valarray;

std::valarray is the class for representing and manipulating arrays of values. It supports element-wise mathematical operations and various forms of generalized subscript operators, slicing and indirect access.

Notes

std::valarray and helper classes are defined to be free of certain forms of aliasing, thus allowing operations on these classes to be optimized similar to the effect of the keyword restrict in the C programming language. In addition, functions and operators that take valarray arguments are allowed to return proxy objects to make it possible for the compiler to optimize an expression such as v1 = a*v2 + v3; as a single loop that executes v1[i] = a*v2[i] + v3[i]; avoiding any temporaries or multiple passes. However, expression templates make the same optimization technique available for any C++ container, and the majority of numeric libraries prefer expression templates to valarrays for flexibility. Some C++ standard library implementations use expression templates to implement efficient operations on std::valarray (e.g. GNU libstdc++ and LLVM libc++). Only rarely are valarrays optimized any further, as in e.g. Intel Parallel Studio.

Template parameters

T

-

the type of the elements. The type must meet the NumericType requirements

Member types

Member type	Definition
value_type	T

Member functions

(constructor)	constructs new numeric array (public member function)
(destructor)	destructs the numeric array (public member function)
operator=	assigns the contents (public member function)
operator[]	get/set valarray element, slice, or mask (public member function)
operator+operator-operator~operator!	applies a unary arithmetic operator to each element of the valarray (public member function)
operator+=operator-=operator*=operator/=operator%=operator&=operator|=operator^=operator<<=operator>>=	applies compound assignment operator to each element of the valarray (public member function)
swap	swaps with another valarray (public member function)
size	returns the size of valarray (public member function)
resize	changes the size of valarray (public member function)
sum	calculates the sum of all elements (public member function)
min	returns the smallest element (public member function)
max	returns the largest element (public member function)
shift	zero-filling shift the elements of the valarray (public member function)
cshift	circular shift of the elements of the valarray (public member function)
apply	applies a function to every element of a valarray (public member function)

Non-member functions

std::swap(std::valarray) (C++11)	specializes the std::swap() algorithm (function template)
std::begin(std::valarray) (C++11)	specializes std::begin (function template)
std::end(std::valarray) (C++11)	specializes std::end (function template)
operator+operator-operator*operator/operator%operator&operator|operator^operator<<operator>>operator&&operator||	applies binary operators to each element of two valarrays, or a valarray and a value (function template)
operator==operator!=operator<operator<=operator>operator>=	compares two valarrays or a valarray with a value (function template)
abs(std::valarray)	applies the function std::abs to each element of valarray (function template)
Exponential functions
exp(std::valarray)	applies the function std::exp to each element of valarray (function template)
log(std::valarray)	applies the function std::log to each element of valarray (function template)
log10(std::valarray)	applies the function std::log10 to each element of valarray (function template)
Power functions
pow(std::valarray)	applies the function std::pow to two valarrays or a valarray and a value (function template)
sqrt(std::valarray)	applies the function std::sqrt to each element of valarray (function template)
Trigonometric functions
sin(std::valarray)	applies the function std::sin to each element of valarray (function template)
cos(std::valarray)	applies the function std::cos to each element of valarray (function template)
tan(std::valarray)	applies the function std::tan to each element of valarray (function template)
asin(std::valarray)	applies the function std::asin to each element of valarray (function template)
acos(std::valarray)	applies the function std::acos to each element of valarray (function template)
atan(std::valarray)	applies the function std::atan to each element of valarray (function template)
atan2(std::valarray)	applies the function std::atan2 to a valarray and a value (function template)
Hyperbolic functions
sinh(std::valarray)	applies the function std::sinh to each element of valarray (function template)
cosh(std::valarray)	applies the function std::cosh to each element of valarray (function template)
tanh(std::valarray)	applies the function std::tanh to each element of valarray (function template)

Helper classes

slice	BLAS-like slice of a valarray: starting index, length, stride (class)
slice_array	proxy to a subset of a valarray after applying a slice (class template)
gslice	generalized slice of a valarray: starting index, set of lengths, set of strides (class)
gslice_array	proxy to a subset of a valarray after applying a gslice (class template)
mask_array	proxy to a subset of a valarray after applying a boolean mask operator[] (class template)
indirect_array	proxy to a subset of a valarray after applying indirect operator[] (class template)