Linear Algebra Operations Extensions.Band Symmetric Multiply And Add In Place Method
Definition
Namespace: Numerics.NET.Collections
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.0.3
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.0.3
Overload List
Band | Performs the matrix-vector operation y := alpha*A*x + beta*y, where alpha and beta are scalars, x and y are n element vectors and A is an n by n symmetric band matrix, with k super-diagonals. |
Band | Product of a symmetric band matrix and a vector. |
BandSymmetricMultiplyAndAddInPlace<T>(ILinearAlgebraOperations<T>, MatrixTriangle, Int32, Int32, T, ReadOnlySpan2D<T>, ReadOnlySpanSlice<T>, T, SpanSlice<T>)
Performs the matrix-vector operation y := alpha*A*x + beta*y, where alpha and beta are scalars, x and y are n element vectors and A is an n by n symmetric band matrix, with k super-diagonals.
public static void BandSymmetricMultiplyAndAddInPlace<T>(
this ILinearAlgebraOperations<T> operations,
MatrixTriangle uplo,
int n,
int k,
T alpha,
ReadOnlySpan2D<T> a,
ReadOnlySpanSlice<T> x,
T beta,
SpanSlice<T> y
)
Parameters
- operations ILinearAlgebraOperations<T>
- The object that performs the operation.
- uplo MatrixTriangle
On entry, UPLO specifies whether the upper or lower triangular part of the band matrix A is being supplied as follows: UPLO = 'U' or 'u' The upper triangular part of A is being supplied. UPLO = 'L' or 'l' The lower triangular part of A is being supplied.
- n Int32
On entry, N specifies the order of the matrix A. N must be at least zero.
- k Int32
On entry, K specifies the number of super-diagonals of the matrix A. K must satisfy 0 .le. K.
- alpha T
ALPHA is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha.
- a ReadOnlySpan2D<T>
A is DOUBLE PRECISION array of DIMENSION ( LDA, n ). Before entry with UPLO = 'U' or 'u', the leading ( k + 1 ) by n part of the array A must contain the upper triangular band part of the symmetric matrix, supplied column by column, with the leading diagonal of the matrix in row ( k + 1 ) of the array, the first super-diagonal starting at position 2 in row k, and so on. The top left k by k triangle of the array A is not referenced. The following program segment will transfer the upper triangular part of a symmetric band matrix from conventional full matrix storage to band storage: DO 20, J = 1, N M = K + 1 - J DO 10, I = MAX( 1, J - K ), J A( M + I, J ) = matrix( I, J ) 10 CONTINUE 20 CONTINUE Before entry with UPLO = 'L' or 'l', the leading ( k + 1 ) by n part of the array A must contain the lower triangular band part of the symmetric matrix, supplied column by column, with the leading diagonal of the matrix in row 1 of the array, the first sub-diagonal starting at position 1 in row 2, and so on. The bottom right k by k triangle of the array A is not referenced. The following program segment will transfer the lower triangular part of a symmetric band matrix from conventional full matrix storage to band storage: DO 20, J = 1, N M = 1 - J DO 10, I = J, MIN( N, J + K ) A( M + I, J ) = matrix( I, J ) 10 CONTINUE 20 CONTINUE
On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least ( k + 1 ).
- x ReadOnlySpanSlice<T>
X is DOUBLE PRECISION array of DIMENSION at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the vector x.
On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
- beta T
BETA is DOUBLE PRECISION. On entry, BETA specifies the scalar beta.
- y SpanSlice<T>
Y is DOUBLE PRECISION array of DIMENSION at least ( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y.
On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
Type Parameters
- T
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type ILinearAlgebraOperations<T>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).Remarks
Further Details:
Level 2 LinearAlgebra routine. The vector and matrix arguments are not referenced when N = 0, or M = 0 -- Written on 22-October-1986. Jack Dongarra, Argonne National Lab. Jeremy Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson, Sandia National Labs.
Authors: Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver, NAG Ltd.
Date: November 2011
BandSymmetricMultiplyAndAddInPlace<T, TStorage, TStorage2D>(ILinearAlgebraOperations<T>, MatrixTriangle, Int32, Int32, T, TStorage2D, TStorage, T, TStorage)
Product of a symmetric band matrix and a vector.
public static void BandSymmetricMultiplyAndAddInPlace<T, TStorage, TStorage2D>(
this ILinearAlgebraOperations<T> operations,
MatrixTriangle storedTriangle,
int n,
int k,
T alpha,
TStorage2D a,
TStorage x,
T beta,
TStorage y
)
where TStorage : Object, IStorageSlice<T>
where TStorage2D : Object, IStorage2D<T>
Parameters
- operations ILinearAlgebraOperations<T>
- The linear algebra operations instance used to perform the calculation.
- storedTriangle MatrixTriangle
- Specifies whether the matrix is an upper or lower triangular matrix.
- n Int32
- The number of rows and columns in the matrix a.
- k Int32
- The bandwidth of the matrix a.
- alpha T
- The scalar used to multiply the matrix-vector product.
- a TStorage2D
- A span that contains the elements of the matrix.
- x TStorage
- A reference to a one-dimensional array containing the elements of the vector x.
- beta T
- The scalar used to multiply y.
- y TStorage
- A reference to a one-dimensional array containing the elements of the vector y. The elements of y are overwritten with the result.
Type Parameters
- T
- TStorage
- TStorage2D
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type ILinearAlgebraOperations<T>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).Remarks
This method is similar to the BLAS routine DSBMV.