Package de.labathome.trustconstr.matrix

Class MatrixOps

java.lang.Object

de.labathome.trustconstr.matrix.MatrixOps

public final class MatrixOps
extends Object

Small static helpers that operate on double[] vectors and Matrix instances.

Method Summary

Modifier and Type	Method	Description
static Matrix	diag(double[] diagonal)	Build a sparse diagonal matrix with the given entries on the diagonal.
static double	dot(double[] a, double[] b)	Dot product of two equal-length vectors.
static double	norm2(double[] v)	Euclidean (2-)norm of a vector.
static Matrix	sparse(Matrix A)	Materialise the non-zero entries of a possibly-dense matrix into a SparseMatrix (DOK-backed).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

norm2

public static double norm2(double[] v)

Euclidean (2-)norm of a vector.

Parameters:

v - vector

Returns:

sqrt(sum_i v[i]^2)

dot

public static double dot(double[] a,
 double[] b)

Dot product of two equal-length vectors.

Parameters:

a - left operand

b - right operand (must have the same length as a)

Returns:

sum_i a[i] * b[i]

diag

public static Matrix diag(double[] diagonal)

Build a sparse diagonal matrix with the given entries on the diagonal.

Parameters:

diagonal - length-n array of diagonal values

Returns:

n x n SparseMatrix with the diagonal populated and zeros elsewhere

sparse

public static Matrix sparse(Matrix A)

Materialise the non-zero entries of a possibly-dense matrix into a SparseMatrix (DOK-backed). Used by tests that exercise the sparse code paths against a dense reference.

Parameters:

A - source matrix

Returns:

SparseMatrix with the same shape and non-zero entries