SRC/cpbtrs.f(3)

🫶 SRC/cpbtrs.f(3) 🫶

okay bestie, welcome to the Library Functions Manual entry for SRC/cpbtrs.f — yes, the filename is the whole title, and we're keeping it cute. This is the CPBTRS routine page, and it's giving linear algebra main character energy. 💅

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🎀 NAME 🎀

• SRC/cpbtrs.f — that's the file, bestie. 🫶

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🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines 🧚

   Functions/Subroutines
       subroutine cpbtrs (uplo, n, kd, nrhs, ab, ldab, b, ldb, info)
           CPBTRS

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💅 Function/Subroutine Documentation 💅

   subroutine cpbtrs (character uplo, integer n, integer kd, integer nrhs,
       complex, dimension( ldab, * ) ab, integer ldab, complex, dimension( ldb,
       * ) b, integer ldb, integer info)
       CPBTRS

CPBTRS — that's the routine name, periodt. 👑

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✨ Purpose ✨

CPBTRS solves a system of linear equations A*X = B with a Hermitian positive definite band matrix A using the Cholesky factorization A = U**H*U or A = L*L**H computed by CPBTRF. No cap, that's the whole point. 🌸

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🧸 Parameters 🧸

🫧 UPLO 🫧

• UPLO is CHARACTER*1.
• = 'U': Upper triangular factor stored in AB;
• = 'L': Lower triangular factor stored in AB.

🫧 N 🫧

• N is INTEGER.
• The order of the matrix A. N >= 0.

🫧 KD 🫧

• KD is INTEGER.
• The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KD >= 0.

🫧 NRHS 🫧

• NRHS is INTEGER.
• The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

🫧 AB 🫧

• AB is COMPLEX array, dimension (LDAB,N).
• The triangular factor U or L from the Cholesky factorization A = U**H*U or A = L*L**H of the band matrix A, stored in the first KD+1 rows of the array.
• The j-th column of U or L is stored in the j-th column of the array AB as follows:
  • if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j;
  • if UPLO ='L', AB(1+i-j,j) = L(i,j) for j<=i<=min(n,j+kd).

🫧 LDAB 🫧

• LDAB is INTEGER.
• The leading dimension of the array AB. LDAB >= KD+1.

🫧 B 🫧

• B is COMPLEX array, dimension (LDB,NRHS).
• On entry, the right hand side matrix B.
• On exit, the solution matrix X.

🫧 LDB 🫧

• LDB is INTEGER.
• The leading dimension of the array B. LDB >= max(1,N).

🫧 INFO 🫧

• INFO is INTEGER.
• = 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 120 of file cpbtrs.f.

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🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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💖 LAPACK · Version 3.12.0 · SRC/cpbtrs.f(3) · no date printed in the footer, just this cute sign-off 💖