DSTECT(3)

💖 NAME

Okay bestie, this page is from the Library Functions Manual and it’s titled dstect.f(3). The actual file it’s talking about is:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/dstect.f

That’s the whole iconic path. Slay.

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✨ SYNOPSIS

🌸 Functions/Subroutines

subroutine DSTECT (n, a, b, shift, num)
    DSTECT

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🦋 Function/Subroutine Documentation

subroutine DSTECT (integer n, double precision, dimension( * ) a, double precision, dimension( * ) b, double precision shift, integer num)
    DSTECT

🎀 Purpose

DSTECT counts the number NUM of eigenvalues of a tridiagonal matrix T which are less than or equal to SHIFT. T has diagonal entries A(1), ... , A(N), and offdiagonal entries B(1), ..., B(N-1). See W. Kahan , Report CS41, Computer Science Dept., Stanford University, July 21, 1966.

So yeah, it’s giving “count the eigenvalues on the correct side of the shift” energy 👑.

🍓 Parameters

N

N is INTEGER. It’s the dimension of the tridiagonal matrix T.

A

A is a DOUBLE PRECISION array, dimension (N). These are the diagonal entries of the tridiagonal matrix T.

B

B is a DOUBLE PRECISION array, dimension (N-1). These are the offdiagonal entries of the tridiagonal matrix T.

SHIFT

SHIFT is DOUBLE PRECISION. It’s the shift, used as described under Purpose.

NUM

NUM is INTEGER. It’s the number of eigenvalues of T less than or equal to SHIFT.

👑 Author

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

Definition at line 81 of file dstect.f.

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🌈 Author

Generated automatically by Doxygen for LAPACK from the source code.

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Bye bestie! The footer says LAPACK Version 3.12.0 and points at /home/abui...IG/dstect.f(3) — mwah 💖✨