.TH "TESTING/LIN/dtbt06.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME TESTING/LIN/dtbt06.f .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBdtbt06\fP (rcond, rcondc, uplo, diag, n, kd, ab, ldab, work, rat)" .br .RI "\fBDTBT06\fP " .in -1c .SH "Function/Subroutine Documentation" .PP .SS "subroutine dtbt06 (double precision rcond, double precision rcondc, character uplo, character diag, integer n, integer kd, double precision, dimension( ldab, * ) ab, integer ldab, double precision, dimension( * ) work, double precision rat)" .PP \fBDTBT06\fP .PP \fBPurpose:\fP .RS 4 .PP .nf DTBT06 computes a test ratio comparing RCOND (the reciprocal condition number of a triangular matrix A) and RCONDC, the estimate computed by DTBCON\&. Information about the triangular matrix A is used if one estimate is zero and the other is non-zero to decide if underflow in the estimate is justified\&. .fi .PP .RE .PP \fBParameters\fP .RS 4 \fIRCOND\fP .PP .nf RCOND is DOUBLE PRECISION The estimate of the reciprocal condition number obtained by forming the explicit inverse of the matrix A and computing RCOND = 1/( norm(A) * norm(inv(A)) )\&. .fi .PP .br \fIRCONDC\fP .PP .nf RCONDC is DOUBLE PRECISION The estimate of the reciprocal condition number computed by DTBCON\&. .fi .PP .br \fIUPLO\fP .PP .nf UPLO is CHARACTER Specifies whether the matrix A is upper or lower triangular\&. = 'U': Upper triangular = 'L': Lower triangular .fi .PP .br \fIDIAG\fP .PP .nf DIAG is CHARACTER Specifies whether or not the matrix A is unit triangular\&. = 'N': Non-unit triangular = 'U': Unit triangular .fi .PP .br \fIN\fP .PP .nf N is INTEGER The order of the matrix A\&. N >= 0\&. .fi .PP .br \fIKD\fP .PP .nf KD is INTEGER The number of superdiagonals or subdiagonals of the triangular band matrix A\&. KD >= 0\&. .fi .PP .br \fIAB\fP .PP .nf AB is DOUBLE PRECISION array, dimension (LDAB,N) The upper or lower triangular band matrix A, stored in the first kd+1 rows of the array\&. The j-th column of A is stored in the j-th column of the array AB as follows: if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd)\&. .fi .PP .br \fILDAB\fP .PP .nf LDAB is INTEGER The leading dimension of the array AB\&. LDAB >= KD+1\&. .fi .PP .br \fIWORK\fP .PP .nf WORK is DOUBLE PRECISION array, dimension (N) .fi .PP .br \fIRAT\fP .PP .nf RAT is DOUBLE PRECISION The test ratio\&. If both RCOND and RCONDC are nonzero, RAT = MAX( RCOND, RCONDC )/MIN( RCOND, RCONDC ) - 1\&. If RAT = 0, the two estimates are exactly the same\&. .fi .PP .RE .PP \fBAuthor\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP .PP Definition at line \fB123\fP of file \fBdtbt06\&.f\fP\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.