[section:inner_product inner_product]

[heading Prototype]

``
template<class SinglePassRange1,
         class SinglePassRange2,
         class Value>
    Value inner_product( const SinglePassRange1& rng1,
                         const SinglePassRange2& rng2,
                         Value                   init );

template<class SinglePassRange1,
         class SinglePassRange2,
         class Value,
         class BinaryOperation1,
         class BinaryOperation2>
    Value inner_product( const SinglePassRange1& rng1,
                         const SinglePassRange2& rng2,
                         Value                   init,
                         BinaryOperation1        op1 );
``

[heading Description]

`inner_product` calculates a generalised inner product of the range `rng1` and `rng2`.

For further information on the `inner_product` algorithm please see __sgi_inner_product__.

[heading Definition]

Defined in the header file `boost/range/numeric.hpp`

[heading Requirements]

[heading For the first version]

# `SinglePassRange1` is a model of the __single_pass_range__ Concept.
# `SinglePassRange2` is a model of the __single_pass_range__ Concept.
# `Value` is a model of the `AssignableConcept`.
# If `x` is an object of type `Value`, `y` is an object of `SinglePassRange1`'s value
type, and `z` is an object of `SinglePassRange2`'s value type, then `x + y * z`
is defined.
# The result type of the expression `x + y * z` is convertible to `Value`.

[heading For the second version]

# `SinglePassRange1` is a model of the __single_pass_range__ Concept.
# `SinglePassRange2` is a model of the __single_pass_range__ Concept.
# `Value` is a model of the `AssignableConcept`.
# `BinaryOperation1` is a model of the `BinaryFunctionConcept`.
# `BinaryOperation2` is a model of the `BinaryFunctionConcept`.
# The value type of `SinglePassRange1` is convertible to the first argument type of `BinaryOperation2`.
# The value type of `SinglePassRange2` is convertible to the second argument type of `BinaryOperation2`.
# `Value` is convertible to the value type of `BinaryOperation1`.
# The return type of `BinaryOperation2` is convertible to the second argument type of `BinaryOperation1`.
# The return type of `BinaryOperation1` is convertible to `Value`.

[heading Precondition:]

`distance(rng2) >= distance(rng1)` is a valid range.

[heading Complexity]

Linear. Exactly `distance(rng)`.

[endsect]