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##### inner_product

###### 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 );

###### Description

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

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

###### Definition

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

###### Requirements

###### For the first version

1. `SinglePassRange1` is a model of the Single Pass Range Concept.
2. `SinglePassRange2` is a model of the Single Pass Range Concept.
3. `Value` is a model of the `AssignableConcept`.
4. 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.
5. The result type of the expression `x + y * z` is convertible to `Value`.

###### For the second version

1. `SinglePassRange1` is a model of the Single Pass Range Concept.
2. `SinglePassRange2` is a model of the Single Pass Range Concept.
3. `Value` is a model of the `AssignableConcept`.
4. `BinaryOperation1` is a model of the `BinaryFunctionConcept`.
5. `BinaryOperation2` is a model of the `BinaryFunctionConcept`.
6. The value type of `SinglePassRange1` is convertible to the first argument type of `BinaryOperation2`.
7. The value type of `SinglePassRange2` is convertible to the second argument type of `BinaryOperation2`.
8. `Value` is convertible to the value type of `BinaryOperation1`.
9. The return type of `BinaryOperation2` is convertible to the second argument type of `BinaryOperation1`.
10. The return type of `BinaryOperation1` is convertible to `Value`.

###### Precondition:

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

###### Complexity

Linear. Exactly `distance(rng)`.