SRC/ztrsyl.f(3)

💅 SRC/ztrsyl.f(3) — Library Functions Manual ✨

🎀 NAME 🎀

SRC/ztrsyl.f — that's literally the name, bestie 💖

✨ SYNOPSIS ✨

Functions/Subroutines

subroutine ztrsyl (trana, tranb, isgn, m, n, a, lda, b, ldb, c, ldc,
    scale, info)
    ZTRSYL

🦋 Function/Subroutine Documentation 🦋

subroutine ztrsyl (character trana, character tranb, integer isgn, integer
    m, integer n, complex*16, dimension( lda, * ) a, integer lda,
    complex*16, dimension( ldb, * ) b, integer ldb, complex*16, dimension(
    ldc, * ) c, integer ldc, double precision scale, integer info)
    ZTRSYL

🌸 Purpose 🌸

Okay so ZTRSYL solves the complex Sylvester matrix equation:

op(A)*X + X*op(B) = scale*C or
op(A)*X - X*op(B) = scale*C,

where op(A) = A or A**H, and A and B are both upper triangular. A is M-by-M and B is N-by-N; the right hand side C and the solution X are M-by-N; and scale is an output scale factor, set <= 1 to avoid overflow in X. Very much giving “we protect X from overflow” energy 🔥

🎀 Parameters 🎀

• TRANA — TRANA is CHARACTER*1. It specifies the option op(A):
  • = 'N': op(A) = A (No transpose)
  • = 'C': op(A) = A**H (Conjugate transpose)
• TRANB — TRANB is CHARACTER*1. It specifies the option op(B):
  • = 'N': op(B) = B (No transpose)
  • = 'C': op(B) = B**H (Conjugate transpose)
• ISGN — ISGN is INTEGER. It specifies the sign in the equation:
  • = +1: solve op(A)*X + X*op(B) = scale*C
  • = -1: solve op(A)*X - X*op(B) = scale*C
• M — M is INTEGER. The order of the matrix A, and the number of rows in the matrices X and C. M >= 0.
• N — N is INTEGER. The order of the matrix B, and the number of columns in the matrices X and C. N >= 0.
• A — A is COMPLEX*16 array, dimension (LDA,M). The upper triangular matrix A.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,M).
• B — B is COMPLEX*16 array, dimension (LDB,N). The upper triangular matrix B.
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• C — C is COMPLEX*16 array, dimension (LDC,N). On entry, the M-by-N right hand side matrix C. On exit, C is overwritten by the solution matrix X.
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• SCALE — SCALE is DOUBLE PRECISION. The scale factor, scale, set <= 1 to avoid overflow in X.
• INFO — INFO is INTEGER.
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value
  • = 1: A and B have common or very close eigenvalues; perturbed values were used to solve the equation (but the matrices A and B are unchanged).

👑 Author 👑

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

Definition at line 155 of file ztrsyl.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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💖 That's a wrap, bestie! This page is from LAPACK Version 3.12.0, and the footer says SRC/ztrsyl.f(3). Periodt. ✨