CPPT03(3)
π CPPT03(3) β Library Functions Manual energy π
okay so this is the CPPT03(3) page, and the header says it's from the Library Functions Manual (title vibe: cppt03.f(3)). bestie, we're about to get into some Hermitian packed-matrix residual math, and honestly? it's giving precise. π
πΈ NAME πΈ
/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/cppt03.f
β¨ SYNOPSIS β¨
π«Ά Functions/Subroutines π«Ά
subroutine CPPT03 (uplo, n, a, ainv, work, ldwork, rwork, rcond, resid)
CPPT03
π οΈ Function/Subroutine Documentation π οΈ
subroutine CPPT03 (character uplo, integer n, complex, dimension( * ) a,
complex, dimension( * ) ainv, complex, dimension( ldwork, * ) work,
integer ldwork, real, dimension( * ) rwork, real rcond, real resid)
CPPT03
π― Purpose π―
CPPT03 computes the residual for a Hermitian packed matrix times its inverse, and the formula is literally this:
norm( I - A*AINV ) / ( N * norm(A) * norm(AINV) * EPS ),
where EPS is the machine epsilon. no cap, that's the whole mission. π
π§Ύ Parameters π§Ύ
UPLOβUPLOisCHARACTER*1; it says whether the upper or lower triangular part of the Hermitian matrixAis stored:= 'U': Upper triangular= 'L': Lower triangular
NβNisINTEGER; it's the number of rows and columns of the matrixA. Constraint:N >= 0.AβAisCOMPLEX array, dimension (N*(N+1)/2); this is the original Hermitian matrixA, stored as a packed triangular matrix.AINVβAINVisCOMPLEX array, dimension (N*(N+1)/2); this is the (Hermitian) inverse of the matrixA, stored as a packed triangular matrix.WORKβWORKisCOMPLEX array, dimension (LDWORK,N).LDWORKβLDWORKisINTEGER; it's the leading dimension of the arrayWORK. Constraint:LDWORK >= max(1,N).RWORKβRWORKisREAL array, dimension (N).RCONDβRCONDisREAL; it's the reciprocal of the condition number ofA, computed as( 1/norm(A) ) / norm(AINV).RESIDβRESIDisREAL; it'snorm(I - A*AINV) / ( N * norm(A) * norm(AINV) * EPS ).
βοΈ Author βοΈ
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
π Definition at line π
Definition at line 108 of file cppt03.f.
π Author π
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