BLAS/SRC/zsyr2k.f(3)

💖 NAME 💖

BLAS/SRC/zsyr2k.f

Okay bestie, this page is from the Library Functions Manual — manual-name info folded in near the top instead of copy-pasting the header line, periodt. ✨

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✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine zsyr2k (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c, ldc) — ZSYR2K

subroutine zsyr2k (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c, ldc)

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🌸 Function/Subroutine Documentation 🌸

🎀 subroutine zsyr2k 🎀

This is the full signature, exactly as declared:

       subroutine zsyr2k (character uplo, character trans, integer n, integer k,
           complex*16 alpha, complex*16, dimension(lda,*) a, integer lda,
           complex*16, dimension(ldb,*) b, integer ldb, complex*16 beta,
           complex*16, dimension(ldc,*) c, integer ldc)

This one is ZSYR2K, and she is serving BLAS realness. 💅

💖 Purpose 💖

ZSYR2K performs one of the symmetric rank 2k operations:

C := alpha*A*B**T + alpha*B*A**T + beta*C,

or

C := alpha*A**T*B + alpha*B**T*A + beta*C,

where alpha and beta are scalars, C is an n by n symmetric matrix, and A and B are n by k matrices in the first case and k by n matrices in the second case.

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💅 Parameters 💅

• UPLO — UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the array C is to be referenced as follows:
  • UPLO = 'U' or 'u' — Only the upper triangular part of C is to be referenced.
  • UPLO = 'L' or 'l' — Only the lower triangular part of C is to be referenced.
• TRANS — TRANS is CHARACTER*1 On entry, TRANS specifies the operation to be performed as follows:
  • TRANS = 'N' or 'n' — C := alpha*A*B**T + alpha*B*A**T + beta*C.
  • TRANS = 'T' or 't' — C := alpha*A**T*B + alpha*B**T*A + beta*C.
• N — N is INTEGER On entry, N specifies the order of the matrix C. N must be at least zero.
• K — K is INTEGER On entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrices A and B, and on entry with TRANS = 'T' or 't', K specifies the number of rows of the matrices A and B. K must be at least zero.
• ALPHA — ALPHA is COMPLEX*16 On entry, ALPHA specifies the scalar alpha.
• A — A is COMPLEX*16 array, dimension ( LDA, ka ), where ka is k when TRANS = 'N' or 'n', and is n otherwise. Before entry with TRANS = 'N' or 'n', the leading n by k part of the array A must contain the matrix A; otherwise, the leading k by n part of the array A must contain the matrix A.
• LDA — LDA is INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When TRANS = 'N' or 'n' then LDA must be at least max( 1, n ), otherwise LDA must be at least max( 1, k ).
• B — B is COMPLEX*16 array, dimension ( LDB, kb ), where kb is k when TRANS = 'N' or 'n', and is n otherwise. Before entry with TRANS = 'N' or 'n', the leading n by k part of the array B must contain the matrix B; otherwise, the leading k by n part of the array B must contain the matrix B.
• LDB — LDB is INTEGER On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. When TRANS = 'N' or 'n' then LDB must be at least max( 1, n ), otherwise LDB must be at least max( 1, k ).
• BETA — BETA is COMPLEX*16 On entry, BETA specifies the scalar beta.
• C — C is COMPLEX*16 array, dimension ( LDC, N ) Before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array C must contain the upper triangular part of the symmetric matrix, and the strictly lower triangular part of C is not referenced. On exit, the upper triangular part of the array C is overwritten by the upper triangular part of the updated matrix.

Before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array C must contain the lower triangular part of the symmetric matrix, and the strictly upper triangular part of C is not referenced. On exit, the lower triangular part of the array C is overwritten by the lower triangular part of the updated matrix.

• LDC — LDC is INTEGER On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max( 1, n ).

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👑 Author 👑

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

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🧚 Further Details 🧚

• Level 3 Blas routine.
• -- Written on 8-February-1989.
  • Jack Dongarra, Argonne National Laboratory.
  • Iain Duff, AERE Harwell.
  • Jeremy Du Croz, Numerical Algorithms Group Ltd.
  • Sven Hammarling, Numerical Algorithms Group Ltd.

Definition at line 187 of file zsyr2k.f.

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💌 Author 💌

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