tinyvector.texi

c++经典教材 Blitz++ v0.8

@findex TinyVector
@cindex TinyVector

The @code{TinyVector} class provides a small, lightweight vector object
whose size is known at compile time.  It is included via the header
@code{<blitz/tinyvec.h>}.  

Note that @code{TinyVector} lives in the @code{blitz} namespace, so you will
need to refer to it as @code{blitz::TinyVector}, or use the directive
@code{using namespace blitz;}.

The Blitz++ @code{Array} object uses @code{TinyVector} internally, so if you
include @code{<blitz/array.h>}, the @code{TinyVector} header is automatically
included.  However, to use @code{TinyVector} expressions, you will
need to include @code{<blitz/tinyvec-et.h>}.

@section Template parameters and types

The @code{TinyVector<T,N>} class has two template parameters:

@table @code
@item T
is the numeric type of the vector (float, double, int,
@code{complex<float>}, etc.;

@item N 
is the number of elements in the vector.
@end table

Inside the @code{TinyVector} class, these types are declared:

@table @code
@item T_numtype
is the numeric type stored in the vector (the template parameter @code{T})

@item T_vector
is the vector type @code{TinyVector<T,N>}.

@item iterator
is an STL-style iterator.

@item constIterator
is an STL-style const iterator.
@end table

@section Constructors

@example
TinyVector();
@end example
The elements of the vector are left uninitialized.

@example
TinyVector(const TinyVector<T,N>& x);
@end example
The elements of vector @code{x} are copied.

@example
TinyVector(T value);
@end example
All elements are initialized to @code{value}.

@example
TinyVector(T value1, T value2, ...);
@end example
The vector is initialized with the list of values given.
These constructors are provided for up to N=11.

@section Member functions

@example
TinyVector<T,N>::iterator                   begin();
TinyVector<T,N>::const_iterator             begin() const;
@end example
Returns an STL-style iterator for the vector, positioned
at the beginning of the data.

@example
TinyVector<T,N>::iterator                   end();
TinyVector<T,N>::const_iterator             end() const;
@end example
Returns an STL-style iterator for the vector, positioned
at the end of the data.

@example
T_numtype* [restrict]                       data();
const T_numtype* [restrict]                 data() const;
@end example
Returns a pointer to the first element in the vector.

@example
int                                         length() const;
@end example
Returns the length of the vector (the template parameter @code{N}).

@example
T_numtype                                   operator()(int i) const;
T_numtype&                                  operator()(int i);
T_numtype                                   operator[](int i) const;
T_numtype&                                  operator[](int i);
@end example
Returns the @code{i}th element of the vector.  If the code is compiled with
debugging enabled (@code{-DBZ_DEBUG}), bounds checking is performed.

@section Assignment operators

The assignment operators =, +=, -=, *=, /=, %=, ^=, &=, |=, >>= and <<= are
all provided.  The right hand side of an assignment may be a scalar of type
@code{T_numtype}, a @code{TinyVector} of any type but the same size, or a
vector expression.

@section Expressions

Expressions involving tiny vectors may contain any combination
of the operators

@example
+ - * / % ^ & | >> <<
@end example

with operands of type TinyVector, scalar, or vector expressions.
The usual math functions (see the Array documentation) are supported
on TinyVector.

@section Global functions

@example
dot(TinyVector, TinyVector);
dot(vector-expr, TinyVector);
dot(TinyVector, vector-expr);
dot(vector-expr, vector-expr);
@end example
These functions calculate a dot product between @code{TinyVector}s
(or vector expressions).  The result is a scalar; the type
of the scalar follows the usual type promotion rules.

@example
product(TinyVector);
@end example
Returns the product of all the elements in the vector.

@example
sum(TinyVector);
@end example
Returns the sum of the elements in the vector.

@example
TinyVector<T,3> cross(TinyVector<T,3> x, TinyVector<T,3> y);
@end example
Returns the cross product of @code{x} and @code{y}.

@section Arrays of @code{TinyVector}

@section Input/output

@example
ostream& operator<<(ostream&, const TinyVector<T,N>& x);
@end example
This function outputs a @code{TinyVector} onto a stream.  Here's
an illustration of the format for a length 3 vector:

@example
[        0.5       0.2       0.9 ]
@end example