SRC/zlascl.f(3)

💅 SRC/zlascl.f

okay so this is a page from the LAPACK manual — Library Functions Manual energy — and honestly? it's a little icon. let's get into it 🫶

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✨ SYNOPSIS ✨

Functions/Subroutines

subroutine zlascl (type, kl, ku, cfrom, cto, m, n, a, lda, info)

ZLASCL multiplies a general rectangular matrix by a real scalar defined as cto/cfrom. that's the whole vibe. 💫

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🌸 Function/Subroutine Documentation 🌸

subroutine zlascl (character type, integer kl, integer ku, double precision
    cfrom, double precision cto, integer m, integer n, complex*16,
    dimension( lda, * ) a, integer lda, integer info)

ZLASCL multiplies a general rectangular matrix by a real scalar defined as cto/cfrom. bestie it literally says it twice, they really wanted us to know 😭

🎀 Purpose 🎀

ZLASCL multiplies the M by N complex matrix A by the real scalar CTO/CFROM. This is done without over/underflow as long as the final result CTO*A(I,J)/CFROM does not over/underflow. TYPE specifies that A may be full, upper triangular, lower triangular, upper Hessenberg, or banded.

so the whole point is: do the scaling safely, no nasty overflow/underflow situations, no cap. ✨ and TYPE is the main character that tells it what kind of storage A is rocking. 💅

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👑 Parameters 👑

• TYPE — TYPE is CHARACTER*1. it indices the storage type of the input matrix (yes, "indices", that's what it says, we love a quirky verb 🦋):
  • = 'G': A is a full matrix.
  • = 'L': A is a lower triangular matrix.
  • = 'U': A is an upper triangular matrix.
  • = 'H': A is an upper Hessenberg matrix.
  • = 'B': A is a symmetric band matrix with lower bandwidth KL and upper bandwidth KU and with the only the lower half stored.
  • = 'Q': A is a symmetric band matrix with lower bandwidth KL and upper bandwidth KU and with the only the upper half stored.
  • = 'Z': A is a band matrix with lower bandwidth KL and upper bandwidth KU. See ZGBTRF for storage details.
• KL — KL is INTEGER. the lower bandwidth of A. referenced only if TYPE = 'B', 'Q' or 'Z'. otherwise she's just sitting there, unbothered. 💀
• KU — KU is INTEGER. the upper bandwidth of A. also referenced only if TYPE = 'B', 'Q' or 'Z'. twins fr fr. 🫶
• CFROM — CFROM is DOUBLE PRECISION.
• CTO — CTO is DOUBLE PRECISION. the matrix A is multiplied by CTO/CFROM. A(I,J) is computed without over/underflow if the final result CTO*A(I,J)/CFROM can be represented without over/underflow. and ⚠️ CFROM must be nonzero — like, genuinely, don't do that. 🚨
• M — M is INTEGER. the number of rows of the matrix A. M >= 0.
• N — N is INTEGER. the number of columns of the matrix A. N >= 0.
• A — A is COMPLEX*16 array, dimension (LDA,N). the matrix to be multiplied by CTO/CFROM. see TYPE for the storage type. she's the star of the show, obviously. ⭐
• LDA — LDA is INTEGER. the leading dimension of the array A. the rules, gorgeous:
  • If TYPE = 'G', 'L', 'U', 'H', LDA >= max(1,M);
  • TYPE = 'B', LDA >= KL+1;
  • TYPE = 'Q', LDA >= KU+1;
  • TYPE = 'Z', LDA >= 2*KL+KU+1.
• INFO — INFO is INTEGER. the vibe check at the end:
  • 0 — successful exit 🎉
  • <0 — if INFO = -i, the i-th argument had an illegal value. 🙈

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🦋 Author 🦋

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

Definition at line 142 of file zlascl.f.

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💖 Author 💖

Generated automatically by Doxygen for LAPACK from the source code. she was built by the machines, no notes. 🤖✨

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aaaand that's the whole page, bestie — literally every line accounted for, ate and left no crumbs. 💅

LAPACK — Version 3.12.0 — SRC/zlascl.f(3) 🎀 mwah, go scale some matrices responsibly 🦋💜