ZUPGTR(3)

💖 ZUPGTR(3) 💖

Hey bestie! This is ZUPGTR(3) from the Library Functions Manual — LAPACK math but make it cute. ✨

💖 NAME 💖

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/zupgtr.f

That’s the whole name path, fr fr.

✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

• subroutine ZUPGTR (uplo, n, ap, tau, q, ldq, work, info) — ZUPGTR

🫶 FUNCTION/SUBROUTINE DOCUMENTATION 🫶

subroutine ZUPGTR (character uplo, integer n, complex*16, dimension( * ) ap, complex*16, dimension( * ) tau, complex*16, dimension( ldq, * ) q, integer ldq, complex*16, dimension( * ) work, integer info)

It’s giving ZUPGTR. 👑

🎯 Purpose 🎯

Okay so ZUPGTR generates a complex unitary matrix Q — it’s defined as the product of n-1 elementary reflectors H(i) of order n, exactly how ZHPTRD returns them using packed storage:

if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),

if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).

Obsessed with a clean packed-storage moment. 🎀

🌈 Parameters 🌈

• UPLO — UPLO is CHARACTER*1
  • = 'U': upper-triangular packed storage was used in the previous call to ZHPTRD;
  • = 'L': lower-triangular packed storage was used in the previous call to ZHPTRD.
• N — N is INTEGER
  • the order of the matrix Q; N >= 0.
• AP — AP is COMPLEX*16 array, dimension (N*(N+1)/2)
  • the vectors that define the elementary reflectors, exactly as returned by ZHPTRD.
• TAU — TAU is COMPLEX*16 array, dimension (N-1)
  • TAU(i) has to hold the scalar factor of elementary reflector H(i), as returned by ZHPTRD.
• Q — Q is COMPLEX*16 array, dimension (LDQ,N)
  • the N-by-N unitary matrix Q.
• LDQ — LDQ is INTEGER
  • the leading dimension of the array Q; LDQ >= max(1,N).
• WORK — WORK is COMPLEX*16 array, dimension (N-1)
• INFO — INFO is INTEGER
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument got an illegal value

🫶 Author 🫶

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

Definition at line 113 of file zupgtr.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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Cute sign-off time, bestie: source/version is LAPACK Version 3.12.0, page path is /home/abui...RC/zupgtr.f(3), and this footer doesn’t print a date — so no invented date, just vibes and the Doxygen note above. 💅💖