org.apache.commons.math.linear

## Interface FieldVector<T extends FieldElement<T>>

• Type Parameters:
`T` - the type of the field elements
All Known Implementing Classes:
ArrayFieldVector, SparseFieldVector

`public interface FieldVector<T extends FieldElement<T>>`
Interface defining a field-valued vector with basic algebraic operations.

vector element indexing is 0-based -- e.g., `getEntry(0)` returns the first element of the vector.

The various `mapXxx` and `mapXxxToSelf` methods operate on vectors element-wise, i.e. they perform the same operation (adding a scalar, applying a function ...) on each element in turn. The `mapXxx` versions create a new vector to hold the result and do not change the instance. The `mapXxxToSelf` versions use the instance itself to store the results, so the instance is changed by these methods. In both cases, the result vector is returned by the methods, this allows to use the fluent API style, like this:

```   RealVector result = v.mapAddToSelf(3.0).mapTanToSelf().mapSquareToSelf();
```
Since:
2.0
• ### Method Summary

All Methods
Modifier and Type Method and Description
`FieldVector<T>` `add(FieldVector<T> v)`
Compute the sum of this and v.
`FieldVector<T>` `add(T[] v)`
Compute the sum of this and v.
`FieldVector<T>` `append(FieldVector<T> v)`
Construct a vector by appending a vector to this vector.
`FieldVector<T>` `append(T d)`
Construct a vector by appending a T to this vector.
`FieldVector<T>` `append(T[] a)`
Construct a vector by appending a T array to this vector.
`FieldVector<T>` `copy()`
Returns a (deep) copy of this.
`T` `dotProduct(FieldVector<T> v)`
Compute the dot product.
`T` `dotProduct(T[] v)`
Compute the dot product.
`FieldVector<T>` `ebeDivide(FieldVector<T> v)`
Element-by-element division.
`FieldVector<T>` `ebeDivide(T[] v)`
Element-by-element division.
`FieldVector<T>` `ebeMultiply(FieldVector<T> v)`
Element-by-element multiplication.
`FieldVector<T>` `ebeMultiply(T[] v)`
Element-by-element multiplication.
`T[]` `getData()`
Returns vector entries as a T array.
`int` `getDimension()`
Returns the size of the vector.
`T` `getEntry(int index)`
Returns the entry in the specified index.
`Field<T>` `getField()`
Get the type of field elements of the vector.
`FieldVector<T>` ```getSubVector(int index, int n)```
Get a subvector from consecutive elements.
`FieldVector<T>` `mapAdd(T d)`
Map an addition operation to each entry.
`FieldVector<T>` `mapAddToSelf(T d)`
Map an addition operation to each entry.
`FieldVector<T>` `mapDivide(T d)`
Map a division operation to each entry.
`FieldVector<T>` `mapDivideToSelf(T d)`
Map a division operation to each entry.
`FieldVector<T>` `mapInv()`
Map the 1/x function to each entry.
`FieldVector<T>` `mapInvToSelf()`
Map the 1/x function to each entry.
`FieldVector<T>` `mapMultiply(T d)`
Map a multiplication operation to each entry.
`FieldVector<T>` `mapMultiplyToSelf(T d)`
Map a multiplication operation to each entry.
`FieldVector<T>` `mapSubtract(T d)`
Map a subtraction operation to each entry.
`FieldVector<T>` `mapSubtractToSelf(T d)`
Map a subtraction operation to each entry.
`FieldMatrix<T>` `outerProduct(FieldVector<T> v)`
Compute the outer product.
`FieldMatrix<T>` `outerProduct(T[] v)`
Compute the outer product.
`FieldVector<T>` `projection(FieldVector<T> v)`
Find the orthogonal projection of this vector onto another vector.
`FieldVector<T>` `projection(T[] v)`
Find the orthogonal projection of this vector onto another vector.
`void` `set(T value)`
Set all elements to a single value.
`void` ```setEntry(int index, T value)```
Set a single element.
`void` ```setSubVector(int index, FieldVector<T> v)```
Set a set of consecutive elements.
`void` ```setSubVector(int index, T[] v)```
Set a set of consecutive elements.
`FieldVector<T>` `subtract(FieldVector<T> v)`
Compute this minus v.
`FieldVector<T>` `subtract(T[] v)`
Compute this minus v.
`T[]` `toArray()`
Convert the vector to a T array.
• ### Method Detail

• #### getField

`Field<T> getField()`
Get the type of field elements of the vector.
Returns:
type of field elements of the vector
• #### copy

`FieldVector<T> copy()`
Returns a (deep) copy of this.
Returns:
vector copy

```FieldVector<T> add(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Compute the sum of this and v.
Parameters:
`v` - vector to be added
Returns:
this + v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this

```FieldVector<T> add(T[] v)
throws java.lang.IllegalArgumentException```
Compute the sum of this and v.
Parameters:
`v` - vector to be added
Returns:
this + v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### subtract

```FieldVector<T> subtract(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Compute this minus v.
Parameters:
`v` - vector to be subtracted
Returns:
this + v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### subtract

```FieldVector<T> subtract(T[] v)
throws java.lang.IllegalArgumentException```
Compute this minus v.
Parameters:
`v` - vector to be subtracted
Returns:
this + v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this

`FieldVector<T> mapAdd(T d)`
Map an addition operation to each entry.
Parameters:
`d` - value to be added to each entry
Returns:
this + d

`FieldVector<T> mapAddToSelf(T d)`
Map an addition operation to each entry.

The instance is changed by this method.

Parameters:
`d` - value to be added to each entry
Returns:
for convenience, return this
• #### mapSubtract

`FieldVector<T> mapSubtract(T d)`
Map a subtraction operation to each entry.
Parameters:
`d` - value to be subtracted to each entry
Returns:
this - d
• #### mapSubtractToSelf

`FieldVector<T> mapSubtractToSelf(T d)`
Map a subtraction operation to each entry.

The instance is changed by this method.

Parameters:
`d` - value to be subtracted to each entry
Returns:
for convenience, return this
• #### mapMultiply

`FieldVector<T> mapMultiply(T d)`
Map a multiplication operation to each entry.
Parameters:
`d` - value to multiply all entries by
Returns:
this * d
• #### mapMultiplyToSelf

`FieldVector<T> mapMultiplyToSelf(T d)`
Map a multiplication operation to each entry.

The instance is changed by this method.

Parameters:
`d` - value to multiply all entries by
Returns:
for convenience, return this
• #### mapDivide

`FieldVector<T> mapDivide(T d)`
Map a division operation to each entry.
Parameters:
`d` - value to divide all entries by
Returns:
this / d
• #### mapDivideToSelf

`FieldVector<T> mapDivideToSelf(T d)`
Map a division operation to each entry.

The instance is changed by this method.

Parameters:
`d` - value to divide all entries by
Returns:
for convenience, return this
• #### mapInv

`FieldVector<T> mapInv()`
Map the 1/x function to each entry.
Returns:
a vector containing the result of applying the function to each entry
• #### mapInvToSelf

`FieldVector<T> mapInvToSelf()`
Map the 1/x function to each entry.

The instance is changed by this method.

Returns:
for convenience, return this
• #### ebeMultiply

```FieldVector<T> ebeMultiply(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Element-by-element multiplication.
Parameters:
`v` - vector by which instance elements must be multiplied
Returns:
a vector containing this[i] * v[i] for all i
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### ebeMultiply

```FieldVector<T> ebeMultiply(T[] v)
throws java.lang.IllegalArgumentException```
Element-by-element multiplication.
Parameters:
`v` - vector by which instance elements must be multiplied
Returns:
a vector containing this[i] * v[i] for all i
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### ebeDivide

```FieldVector<T> ebeDivide(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Element-by-element division.
Parameters:
`v` - vector by which instance elements must be divided
Returns:
a vector containing this[i] / v[i] for all i
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### ebeDivide

```FieldVector<T> ebeDivide(T[] v)
throws java.lang.IllegalArgumentException```
Element-by-element division.
Parameters:
`v` - vector by which instance elements must be divided
Returns:
a vector containing this[i] / v[i] for all i
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### getData

`T[] getData()`
Returns vector entries as a T array.
Returns:
T array of entries
• #### dotProduct

```T dotProduct(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Compute the dot product.
Parameters:
`v` - vector with which dot product should be computed
Returns:
the scalar dot product between instance and v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### dotProduct

```T dotProduct(T[] v)
throws java.lang.IllegalArgumentException```
Compute the dot product.
Parameters:
`v` - vector with which dot product should be computed
Returns:
the scalar dot product between instance and v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### projection

```FieldVector<T> projection(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Find the orthogonal projection of this vector onto another vector.
Parameters:
`v` - vector onto which instance must be projected
Returns:
projection of the instance onto v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### projection

```FieldVector<T> projection(T[] v)
throws java.lang.IllegalArgumentException```
Find the orthogonal projection of this vector onto another vector.
Parameters:
`v` - vector onto which instance must be projected
Returns:
projection of the instance onto v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### outerProduct

```FieldMatrix<T> outerProduct(FieldVector<T> v)
throws java.lang.IllegalArgumentException```
Compute the outer product.
Parameters:
`v` - vector with which outer product should be computed
Returns:
the square matrix outer product between instance and v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### outerProduct

```FieldMatrix<T> outerProduct(T[] v)
throws java.lang.IllegalArgumentException```
Compute the outer product.
Parameters:
`v` - vector with which outer product should be computed
Returns:
the square matrix outer product between instance and v
Throws:
`java.lang.IllegalArgumentException` - if v is not the same size as this
• #### getEntry

```T getEntry(int index)
throws MatrixIndexException```
Returns the entry in the specified index.

The index start at 0 and must be lesser than the size, otherwise a `MatrixIndexException` is thrown.

Parameters:
`index` - index location of entry to be fetched
Returns:
vector entry at index
Throws:
`MatrixIndexException` - if the index is not valid
`setEntry(int, FieldElement)`
• #### setEntry

```void setEntry(int index,
T value)
throws MatrixIndexException```
Set a single element.
Parameters:
`index` - element index.
`value` - new value for the element.
Throws:
`MatrixIndexException` - if the index is inconsistent with vector size
`getEntry(int)`
• #### getDimension

`int getDimension()`
Returns the size of the vector.
Returns:
size
• #### append

`FieldVector<T> append(FieldVector<T> v)`
Construct a vector by appending a vector to this vector.
Parameters:
`v` - vector to append to this one.
Returns:
a new vector
• #### append

`FieldVector<T> append(T d)`
Construct a vector by appending a T to this vector.
Parameters:
`d` - T to append.
Returns:
a new vector
• #### append

`FieldVector<T> append(T[] a)`
Construct a vector by appending a T array to this vector.
Parameters:
`a` - T array to append.
Returns:
a new vector
• #### getSubVector

```FieldVector<T> getSubVector(int index,
int n)
throws MatrixIndexException```
Get a subvector from consecutive elements.
Parameters:
`index` - index of first element.
`n` - number of elements to be retrieved.
Returns:
a vector containing n elements.
Throws:
`MatrixIndexException` - if the index is inconsistent with vector size
• #### setSubVector

```void setSubVector(int index,
FieldVector<T> v)
throws MatrixIndexException```
Set a set of consecutive elements.
Parameters:
`index` - index of first element to be set.
`v` - vector containing the values to set.
Throws:
`MatrixIndexException` - if the index is inconsistent with vector size
`setSubVector(int, FieldElement[])`
• #### setSubVector

```void setSubVector(int index,
T[] v)
throws MatrixIndexException```
Set a set of consecutive elements.
Parameters:
`index` - index of first element to be set.
`v` - vector containing the values to set.
Throws:
`MatrixIndexException` - if the index is inconsistent with vector size
`setSubVector(int, FieldVector)`
• #### set

`void set(T value)`
Set all elements to a single value.
Parameters:
`value` - single value to set for all elements
• #### toArray

`T[] toArray()`
Convert the vector to a T array.

The array is independent from vector data, it's elements are copied.

Returns:
array containing a copy of vector elements