SRC/zunbdb5.f(3)

🌸 NAME 🌸

okay so this page is SRC/zunbdb5.f(3), and it's from the Library Functions Manual. It's the whole ZUNBDB5 vibe: a Fortran subroutine that orthogonalizes a column vector against an orthonormal basis. 💅✨

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

subroutine zunbdb5 (m1, m2, n, x1, incx1, x2, incx2, q1, ldq1, q2, ldq2, work, lwork, info)

ZUNBDB5

💖 Function/Subroutine Documentation 💖

🌟 subroutine zunbdb5

subroutine zunbdb5 (integer m1, integer m2, integer n, complex*16,
    dimension(*) x1, integer incx1, complex*16, dimension(*) x2, integer
    incx2, complex*16, dimension(ldq1,*) q1, integer ldq1, complex*16,
    dimension(ldq2,*) q2, integer ldq2, complex*16, dimension(*) work,
    integer lwork, integer info)

ZUNBDB5

🎀 Purpose 🎀

bestie, here's the whole point: ZUNBDB5 orthogonalizes the column vector

X = [ X1 ]
    [ X2 ]

with respect to the columns of

Q = [ Q1 ] .
    [ Q2 ]

The columns of Q must be orthonormal. Like, that's not optional. 🫶

If the projection is zero according to Kahan's criterion, then some other vector from the orthogonal complement is returned. This vector is chosen in an arbitrary but deterministic way.

this is the exact Kahan's-criterion situation, so keep that detail in mind 💅

💜 Parameters 💜

• M1 — M1 is INTEGER; the dimension of X1 and the number of rows in Q1. 0 <= M1.
• M2 — M2 is INTEGER; the dimension of X2 and the number of rows in Q2. 0 <= M2.
• N — N is INTEGER; the number of columns in Q1 and Q2. 0 <= N.
• X1 — X1 is COMPLEX*16 array, dimension (M1); on entry, the top part of the vector to be orthogonalized. On exit, the top part of the projected vector.
• INCX1 — INCX1 is INTEGER; increment for entries of X1.
• X2 — X2 is COMPLEX*16 array, dimension (M2); on entry, the bottom part of the vector to be orthogonalized. On exit, the bottom part of the projected vector.
• INCX2 — INCX2 is INTEGER; increment for entries of X2.
• Q1 — Q1 is COMPLEX*16 array, dimension (LDQ1, N); the top part of the orthonormal basis matrix.
• LDQ1 — LDQ1 is INTEGER; the leading dimension of Q1. LDQ1 >= M1.
• Q2 — Q2 is COMPLEX*16 array, dimension (LDQ2, N); the bottom part of the orthonormal basis matrix.
• LDQ2 — LDQ2 is INTEGER; the leading dimension of Q2. LDQ2 >= M2.
• WORK — WORK is COMPLEX*16 array, dimension (LWORK).
• LWORK — LWORK is INTEGER; the dimension of the array WORK. LWORK >= N.
• INFO — INFO is INTEGER; = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value.

👑 Author 👑

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 154 of file zunbdb5.f.

🦋 Author 🦋

Generated automatically by Doxygen for LAPACK from the source code.

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and that's the whole page, bestie 💖. The footer vibes are LAPACK, Version 3.12.0, source SRC/zunbdb5.f(3). Mwah 💋✨