`scipy.linalg._fblas:dsbmv`

Signature

def dsbmv(k, alpha, a, x, incx = 1, offx = 0, beta = 0.0, y = None, incy = 1, offy = 0, lower = 0, overwrite_y = 0)

Compute y = alpha*a@x + beta*y for a banded symmetric matrix a (BLAS dsbmv).

k : int: Number of super-diagonals (or sub-diagonals) of the band.
alpha : float: Scalar multiplier for the product.
a : ndarray: Banded storage of the symmetric matrix, shape (k + 1, n).
x : ndarray: Input vector.
incx : int, optional: Stride between successive elements of x. Default is 1.
offx : int, optional: Index of the first element of x to use. Default is 0.
beta : float, optional: Scalar multiplier for y. Default is 0.
y : ndarray, optional: Input/output vector; if omitted a new zero vector is allocated. Default is None.
incy : int, optional: Stride between successive elements of y. Default is 1.
offy : int, optional: Index of the first element of y to use. Default is 0.
lower : int, optional: If 0, the upper triangle is used; if 1, the lower. Default is 0.
overwrite_y : int, optional: If nonzero, y may be overwritten in place. Default is 0.