TESTING/EIG/dsyl01.f(3)

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version 3.12.1 · 3 versions
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🌸 NAME 🌸

TESTING/EIG/dsyl01.f

okay bestie, this is the TESTING/EIG/dsyl01.f(3) page from the Library Functions Manual — yes, the whole file name is the main character here 💅

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

  • subroutine dsyl01 (thresh, nfail, rmax, ninfo, knt) — DSYL01

👑 Function/Subroutine Documentation 👑

🌟 subroutine dsyl01 signature 🌟

subroutine dsyl01 (double precision thresh, integer, dimension( 3 ) nfail,
       double precision, dimension( 2 ) rmax, integer, dimension( 2 ) ninfo,
       integer knt)

DSYL01

🧚 Purpose 🧚

okay so DSYL01 tests DTRSYL and DTRSYL3, routines for solving the Sylvester matrix equation:

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

A and B are assumed to be in Schur canonical form, op() represents an optional transpose, and ISGN can be -1 or +1. Scale is an output less than or equal to 1, chosen to avoid overflow in X.

The test code verifies that the following residual does not exceed the provided threshold:

norm(op(A)*X + ISGN*X*op(B) - scale*C) /
    (EPS*max(norm(A),norm(B))*norm(X))

This routine complements DGET35 by testing with larger, random matrices, of which some require rescaling of X to avoid overflow.

🔥 Parameters 🔥

THRESH

THRESH is DOUBLE PRECISION. A test will count as if the residual, computed as described above, exceeds THRESH.

yes bestie, the source text has a lil blank after “as” — I’m leaving it exactly as-is so I don’t mess with the facts 💀

NFAIL

NFAIL is INTEGER array, dimension (3).

  • NFAIL(1) = No. of times residual DTRSYL exceeds threshold THRESH
  • NFAIL(2) = No. of times residual DTRSYL3 exceeds threshold THRESH
  • NFAIL(3) = No. of times DTRSYL3 and DTRSYL deviate

RMAX

RMAX is DOUBLE PRECISION, dimension (2).

  • RMAX(1) = Value of the largest test ratio of DTRSYL
  • RMAX(2) = Value of the largest test ratio of DTRSYL3

NINFO

NINFO is INTEGER array, dimension (2).

  • NINFO(1) = No. of times DTRSYL returns an expected INFO
  • NINFO(2) = No. of times DTRSYL3 returns an expected INFO

KNT

KNT is INTEGER.

Total number of examples tested.

Definition at line 88 of file dsyl01.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

okay that’s the whole page, bestie — LAPACK Version 3.12.0 TESTING/EIG/dsyl01.f(3). byeee 💖✨🎀

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