Matrix.h

Matrix objects are two-dimensional specializations (e.g., more convenient and efficient indexing) of the general Array class. You might also want to look at the Array documentation to see inherited functionality. A tutorial on using the array classes in general is available in the "AIPS++ Programming Manual".

Generally the member functions of Array are also available in Matrix versions which take a pair of integers where the array needs an IPosition. Since the Matrix is two-dimensional, the IPositions are overkill, although you may use those versions if you want to.

    Matrix<Int> mi(100,100);  // Shape is 100x100
    mi.resize(50,50);         // Shape now 50x50

Slices may be taken with the Slice class. To take a slice, one "indexes" with one Slice(start, length, inc) for each axis, where end and inc are optional. Additionally, there are row(), column() and diagonal() member functions which return Vector's which refer to the storage back in the Matrix:

    Matrix<Float> mf(100, 100);
    mf.diagonal() = 1;

Correct indexing order of a matrix is:

    Matrix<Int> mi(n1,n2)                  // [nrow, ncolumn]
    for (uInt j=0; j<mi.ncolumn(); j++) {
       for (uInt i=0; i<mi.nrow(); i++) {
          mi(i,j) = i*j;
       }      
    }

Element-by-element arithmetic and logical operations are available (in aips/ArrayMath.h and aips/ArrayLogical.h). Other Matrix operations (e.g. LU decomposition) are available, and more appear periodically.

As with the Arrays, if the preprocessor symbol AIPS_DEBUG is defined at compile time invariants will be checked on entry to most member functions. Additionally, if AIPS_ARRAY_INDEX_CHECK is defined index operations will be bounds-checked. Neither of these should be defined for production code.

Member Description

Matrix()

A Matrix of length zero in each dimension; zero origin.

Matrix(uInt l1, uInt l2)

A Matrix with "l1" rows and "l2" columns.

Matrix(uInt l1, uInt l2, const T &initialValue)

A Matrix with "l1" rows and "l2" columns. Fill it with the initial value.

Matrix(const IPosition &len)

A matrix of shape with shape "len".

Matrix(const IPosition &len, const T &initialValue)

A matrix of shape with shape "len". Fill it with the initial value.

Matrix(const Matrix<T> &other)

The copy constructor uses reference semantics.

Matrix(const Array<T> &other)

Construct a Matrix by reference from "other". "other must have ndim() of 2 or less.

Matrix(const IPosition &shape, T *storage, StorageInitPolicy policy = COPY)

Create an Matrix of a given shape from a pointer.

Matrix(const IPosition &shape, const T *storage)

Create an Matrix of a given shape from a pointer. Because the pointer is const, a copy is always made.

virtual ~Matrix()

Define a destructor, otherwise the (SUN) compiler makes a static one.

virtual void assign (const Array<T>& other)

Assign the other array (which must be dimension 2) to this matrix. If the shapes mismatch, this array is resized.

virtual void reference(const Array<T> &other)

Make this matrix a reference to other. Other must be of dimensionality 2 or less.

void resize(uInt nx, uInt ny, Bool copyValues=False)
virtual void resize()
virtual void resize(const IPosition &newShape, Bool copyValues=False)

Resize to the given shape (must be 2-dimensional). Resize without argument is equal to resize(0,0).

Matrix<T> &operator=(const Matrix<T> &other)
virtual Array<T> &operator=(const Array<T> &other)

Copy the values from other to this Matrix. If this matrix has zero elements then it will resize to be the same shape as other; otherwise other must conform to this. Note that the assign function can be used to assign a non-conforming matrix.

Array<T> &operator=(const T &val)

Copy val into every element of this Matrix; i.e. behaves as if val were a constant conformant matrix.

Matrix<T> &operator= (const MaskedArray<T> &marray)

Copy to this those values in marray whose corresponding elements in marray's mask are True.

T &operator()(const IPosition &i)
const T &operator()(const IPosition &i) const
T &operator()(uInt i1, uInt i2)
const T &operator()(uInt i1, uInt i2) const

Single-pixel addressing. If AIPS_ARRAY_INDEX_CHECK is defined, bounds checking is performed.

MaskedArray<T> operator() (const LogicalArray &mask)

The array is masked by the input LogicalArray. This mask must conform to the array.

Return a MaskedArray.

MaskedArray<T> operator() (const LogicalArray &mask) const

The array is masked by the input LogicalArray. This mask must conform to the array.

MaskedArray<T> operator() (const MaskedLogicalArray &mask)

The array is masked by the input MaskedLogicalArray. The mask is effectively the AND of the internal LogicalArray and the internal mask of the MaskedLogicalArray. The MaskedLogicalArray must conform to the array.

Return a MaskedArray.

MaskedArray<T> operator() (const MaskedLogicalArray &mask) const

Vector<T> row(uInt i)
Vector<T> row(uInt i) const
const Vector<T> row(uInt i) const

Returns a reference to the i'th row.

Vector<T> column(uInt j)
Vector<T> column(uInt j) const
const Vector<T> column(uInt j) const

Returns a reference to the j'th column

Vector<T> diagonal(Int n)

Returns a diagonal from the Matrix. The Matrix must be square.

n==0 is the main diagonal. n>0 is above the main diagonal, n<0 is below it.

Vector<T> diagonal( )
Vector<T> diagonal( ) const
const Vector<T> diagonal( ) const
Vector<T> diagonal(Int n) const
const Vector<T> diagonal(Int n) const

Returns a diagonal from the Matrix. The Matrix must be square.

Matrix<T> operator()(const Slice &sliceX, const Slice &sliceY)

Take a slice of this matrix. Slices are always indexed starting at zero. This uses reference semantics, i.e. changing a value in the slice changes the original.

    Matrix<Double> vd(100,100);
    //...
    vd(Slice(0,10),Slice(10,10)) = -1.0; // 10x10 sub-matrix set to -1.0

Array<T> operator()(const IPosition &blc, const IPosition &trc, const IPosition &incr)
Array<T> operator()(const IPosition &blc, const IPosition &trc)
Array<T> operator()(const Slicer& slicer)

Slice using IPositions. Required to be defined, otherwise the base class versions are hidden.

void shape(Int &s1, Int &s2) const
const IPosition &shape() const

The length of each axis of the Matrix.

uInt nrow() const

The number of rows in the Matrix, i.e. the length of the first axis.

uInt ncolumn() const

The number of columns in the Matrix, i.e. the length of the 2nd axis.

virtual void takeStorage(const IPosition &shape, const T *storage)

Replace the data values with those in the pointer storage. The results are undefined is storage does not point at nelements() or more data elements. After takeStorage() is called, unique() is True.

Since the pointer is const, a copy is always taken.

virtual void takeStorage(const IPosition &shape, T *storage, StorageInitPolicy policy = COPY)

virtual Bool ok() const

Checks that the Matrix is consistent (invariants check out).

virtual void doNonDegenerate(Array<T> &other, const IPosition &ignoreAxes)

Remove the degenerate axes from other and store result in this matrix. An exception is thrown if removing degenerate axes does not result in a matrix.

void makeIndexingConstants()

Helper fn to calculate the indexing constants.