Method: NMatrix::BLAS.gemv

Defined in:
lib/nmatrix_gemv/blas.rb

.gemv(a, x, y = nil, alpha = 1.0, beta = 0.0, transpose_a = false, m = nil, n = nil, lda = nil, incx = nil, incy = nil) ⇒ Object

call-seq:

gemv(a, x) -> NMatrix
gemv(a, x, y) -> NMatrix
gemv(a, x, y, alpha, beta) -> NMatrix

Implements matrix-vector product via

y = (alpha * A * x) + (beta * y)

where alpha and beta are scalar values.

  • Arguments :

    • a -> Matrix A.

    • x -> Vector x.

    • y -> Vector y.

    • alpha -> A scalar value that multiplies A * x.

    • beta -> A scalar value that multiplies y.

    • transpose_a ->

    • m ->

    • n ->

    • lda ->

    • incx ->

    • incy ->

  • Returns : -

  • Raises :

    • ++ ->

Raises:

  • (ArgumentError) 


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# File 'lib/nmatrix_gemv/blas.rb', line 60

def gemv(a, x, y = nil, alpha = 1.0, beta = 0.0, transpose_a = false, m = nil, n = nil, lda = nil, incx = nil, incy = nil)
  raise(ArgumentError, 'Expected dense NMatrices as first two arguments.') unless a.is_a?(NMatrix) and x.is_a?(NMatrix) and a.stype == :dense and x.stype == :dense
  raise(ArgumentError, 'Expected nil or dense NMatrix as third argument.') unless y.nil? or (y.is_a?(NMatrix) and y.stype == :dense)
  raise(ArgumentError, 'NMatrix dtype mismatch.')                          unless a.dtype == x.dtype and (y ? a.dtype == y.dtype : true)

  m ||= transpose_a ? a.shape[1] : a.shape[0]
  n ||= transpose_a ? a.shape[0] : a.shape[1]

  lda   ||= a.shape[1]
  incx  ||= 1
  incy  ||= 1

  # NM_COMPLEX64 and NM_COMPLEX128 both require complex alpha and beta.
  if a.dtype == :complex64 or a.dtype == :complex128
    alpha = Complex(1.0, 0.0) if alpha == 1.0
    beta  = Complex(0.0, 0.0) if beta  == 0.0
  end

  y ||= NMatrix.new([m, n], dtype: a.dtype)

  NMatrix::BLAS.cblas_gemv(transpose_a, m, n, alpha, a, lda, x, incx, beta, y, incy)

  return y
end