Interface Vector
- All Superinterfaces:
Iterable<VectorEntry>
,Serializable
- All Known Subinterfaces:
ISparseVector
- All Known Implementing Classes:
AbstractVector
,DenseVector
,DistVector
,SparseVector
double
s in an array, and is
used alongside Matrix
in numerical computations. Implementing
classes decides on the actual storage.
Basic operations
Use size
to get the vector size. get(int)
gets
an element, and there are corresponding set(int,double)
and
add(int,double)
methods as well. Note that vector indices are
zero-based (typical for Java and C). This means that they range from 0 to
size-1
. It is legal to have size
equal zero.
Other basic operations are zero
which zeros all the entries of
the vector, which can be cheaper than either zeroing the vector manually, or
creating a new vector, and the operation copy
which creates a
deep copy of the vector. This copy has separate storage, but starts with the
same contents as the current vector.
Iterators
The vector interface extends Iterable
, and the iterator
returns a VectorEntry
which contains current index and entry
value. Note that the iterator may skip non-zero entries. Using an iterator,
many simple and efficient algorithms can be created. The iterator also
permits changing values in the vector, however only non-zero entries can be
changed.
Basic linear algebra
A selection of basic linear algebra operations are available. To ensure high efficiency, little or no internal memory allocation is done, and the user is required to supply the output arguments.
The operations available include:
- Additions
- Vectors can be added to each other, even if their underlying vector structures are incompatible
- Scaling
- Scalar multiplication (scaling) of a whole vector
- Norms
- Both innerproducts and norms can be computed. Several common norms are supported
-
Nested Class Summary
Nested Classes -
Method Summary
Modifier and TypeMethodDescriptionx = alpha*y + x
void
add
(int index, double value) x(index) += value
x = y + x
copy()
Creates a deep copy of the vectordouble
xT*y
double
get
(int index) Returnsx(index)
double
norm
(Vector.Norm type) Computes the given norm of the vectorscale
(double alpha) x=alpha*x
x=alpha*y
void
set
(int index, double value) x(index) = value
x=y
int
size()
Size of the vectorzero()
Zeros all the entries in the vector, while preserving any underlying structureMethods inherited from interface java.lang.Iterable
forEach, iterator, spliterator
-
Method Details
-
size
int size()Size of the vector -
set
void set(int index, double value) x(index) = value
-
add
void add(int index, double value) x(index) += value
-
get
double get(int index) Returnsx(index)
-
copy
Vector copy()Creates a deep copy of the vector -
zero
Vector zero()Zeros all the entries in the vector, while preserving any underlying structure -
scale
x=alpha*x
- Returns:
- x
-
set
x=y
- Returns:
- x
-
set
x=alpha*y
- Returns:
- x
-
add
x = y + x
- Returns:
- x
-
add
x = alpha*y + x
- Returns:
- x
-
dot
xT*y
-
norm
Computes the given norm of the vector- Parameters:
type
- The type of norm to compute
-