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LAPACK 3.3.1
Linear Algebra PACKage
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LAPACK 3.3.1
Linear Algebra PACKage
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00001 DOUBLE PRECISION FUNCTION ZTZT02( M, N, AF, LDA, TAU, WORK, 00002 $ LWORK ) 00003 * 00004 * -- LAPACK test routine (version 3.1) -- 00005 * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. 00006 * November 2006 00007 * 00008 * .. Scalar Arguments .. 00009 INTEGER LDA, LWORK, M, N 00010 * .. 00011 * .. Array Arguments .. 00012 COMPLEX*16 AF( LDA, * ), TAU( * ), WORK( LWORK ) 00013 * .. 00014 * 00015 * Purpose 00016 * ======= 00017 * 00018 * ZTZT02 returns 00019 * || I - Q'*Q || / ( M * eps) 00020 * where the matrix Q is defined by the Householder transformations 00021 * generated by ZTZRQF. 00022 * 00023 * Arguments 00024 * ========= 00025 * 00026 * M (input) INTEGER 00027 * The number of rows of the matrix AF. 00028 * 00029 * N (input) INTEGER 00030 * The number of columns of the matrix AF. 00031 * 00032 * AF (input) COMPLEX*16 array, dimension (LDA,N) 00033 * The output of ZTZRQF. 00034 * 00035 * LDA (input) INTEGER 00036 * The leading dimension of the array AF. 00037 * 00038 * TAU (input) COMPLEX*16 array, dimension (M) 00039 * Details of the Householder transformations as returned by 00040 * ZTZRQF. 00041 * 00042 * WORK (workspace) COMPLEX*16 array, dimension (LWORK) 00043 * 00044 * LWORK (input) INTEGER 00045 * length of WORK array. Must be >= N*N+N 00046 * 00047 * ===================================================================== 00048 * 00049 * .. Parameters .. 00050 DOUBLE PRECISION ZERO, ONE 00051 PARAMETER ( ZERO = 0.0D0, ONE = 1.0D0 ) 00052 * .. 00053 * .. Local Scalars .. 00054 INTEGER I 00055 * .. 00056 * .. Local Arrays .. 00057 DOUBLE PRECISION RWORK( 1 ) 00058 * .. 00059 * .. External Functions .. 00060 DOUBLE PRECISION DLAMCH, ZLANGE 00061 EXTERNAL DLAMCH, ZLANGE 00062 * .. 00063 * .. External Subroutines .. 00064 EXTERNAL XERBLA, ZLASET, ZLATZM 00065 * .. 00066 * .. Intrinsic Functions .. 00067 INTRINSIC DBLE, DCMPLX, DCONJG, MAX 00068 * .. 00069 * .. Executable Statements .. 00070 * 00071 ZTZT02 = ZERO 00072 * 00073 IF( LWORK.LT.N*N+N ) THEN 00074 CALL XERBLA( 'ZTZT02', 7 ) 00075 RETURN 00076 END IF 00077 * 00078 * Quick return if possible 00079 * 00080 IF( M.LE.0 .OR. N.LE.0 ) 00081 $ RETURN 00082 * 00083 * Q := I 00084 * 00085 CALL ZLASET( 'Full', N, N, DCMPLX( ZERO ), DCMPLX( ONE ), WORK, 00086 $ N ) 00087 * 00088 * Q := P(1) * ... * P(m) * Q 00089 * 00090 DO 10 I = M, 1, -1 00091 CALL ZLATZM( 'Left', N-M+1, N, AF( I, M+1 ), LDA, TAU( I ), 00092 $ WORK( I ), WORK( M+1 ), N, WORK( N*N+1 ) ) 00093 10 CONTINUE 00094 * 00095 * Q := P(m)' * ... * P(1)' * Q 00096 * 00097 DO 20 I = 1, M 00098 CALL ZLATZM( 'Left', N-M+1, N, AF( I, M+1 ), LDA, 00099 $ DCONJG( TAU( I ) ), WORK( I ), WORK( M+1 ), N, 00100 $ WORK( N*N+1 ) ) 00101 20 CONTINUE 00102 * 00103 * Q := Q - I 00104 * 00105 DO 30 I = 1, N 00106 WORK( ( I-1 )*N+I ) = WORK( ( I-1 )*N+I ) - ONE 00107 30 CONTINUE 00108 * 00109 ZTZT02 = ZLANGE( 'One-norm', N, N, WORK, N, RWORK ) / 00110 $ ( DLAMCH( 'Epsilon' )*DBLE( MAX( M, N ) ) ) 00111 RETURN 00112 * 00113 * End of ZTZT02 00114 * 00115 END
1.7.3 
