bundles / scipy latest / scipy / linalg / _flapack / dlasd4

lapack_function

`scipy.linalg._flapack:dlasd4`

source: build-install/usr/lib/python3.14/site-packages/scipy/linalg/_flapack.cpython-314-x86_64-linux-gnu.so

Signature

def dlasd4(i, d, z, rho = 1.0)

Summary

Compute one root of the secular equation of a rank-one modified diagonal matrix (LAPACK dlasd4).

Extended Summary

Used by the divide-and-conquer SVD update. LAPACK ships no complex counterpart, so only the real flavors exist.

Parameters

i : int: Which root to compute, 0-based.
d : ndarray: The diagonal, in increasing order.
z : ndarray: The rank-one update vector, the same length as d.
rho : float, optional: Scalar the update is scaled by. Default is 1.0.

Returns

delta : ndarray: The differences d[j] - sigma.
sigma : float: The computed root.
work : ndarray: The sums d[j] + sigma.
info : int: 0 on success; 1 if the iteration failed to converge.

Aliases

scipy.linalg._flapack.dlasd4