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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 REAL FUNCTION STZT02( 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 REAL AF( LDA, * ), TAU( * ), WORK( LWORK ) 00013 * .. 00014 * 00015 * Purpose 00016 * ======= 00017 * 00018 * STZT02 returns 00019 * || I - Q'*Q || / ( M * eps) 00020 * where the matrix Q is defined by the Householder transformations 00021 * generated by STZRQF. 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) REAL array, dimension (LDA,N) 00033 * The output of STZRQF. 00034 * 00035 * LDA (input) INTEGER 00036 * The leading dimension of the array AF. 00037 * 00038 * TAU (input) REAL array, dimension (M) 00039 * Details of the Householder transformations as returned by 00040 * STZRQF. 00041 * 00042 * WORK (workspace) REAL array, dimension (LWORK) 00043 * 00044 * LWORK (input) INTEGER 00045 * length of WORK array. Must be >= N*N+N 00046 * 00047 * ===================================================================== 00048 * 00049 * .. Parameters .. 00050 REAL ZERO, ONE 00051 PARAMETER ( ZERO = 0.0E0, ONE = 1.0E0 ) 00052 * .. 00053 * .. Local Scalars .. 00054 INTEGER I 00055 * .. 00056 * .. Local Arrays .. 00057 REAL RWORK( 1 ) 00058 * .. 00059 * .. External Functions .. 00060 REAL SLAMCH, SLANGE 00061 EXTERNAL SLAMCH, SLANGE 00062 * .. 00063 * .. External Subroutines .. 00064 EXTERNAL SLATZM, SLASET, XERBLA 00065 * .. 00066 * .. Intrinsic Functions .. 00067 INTRINSIC MAX, REAL 00068 * .. 00069 * .. Executable Statements .. 00070 * 00071 STZT02 = ZERO 00072 * 00073 IF( LWORK.LT.N*N+N ) THEN 00074 CALL XERBLA( 'STZT02', 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 SLASET( 'Full', N, N, ZERO, ONE, WORK, N ) 00086 * 00087 * Q := P(1) * ... * P(m) * Q 00088 * 00089 DO 10 I = M, 1, -1 00090 CALL SLATZM( 'Left', N-M+1, N, AF( I, M+1 ), LDA, TAU( I ), 00091 $ WORK( I ), WORK( M+1 ), N, WORK( N*N+1 ) ) 00092 10 CONTINUE 00093 * 00094 * Q := P(m) * ... * P(1) * Q 00095 * 00096 DO 20 I = 1, M 00097 CALL SLATZM( 'Left', N-M+1, N, AF( I, M+1 ), LDA, TAU( I ), 00098 $ WORK( I ), WORK( M+1 ), N, WORK( N*N+1 ) ) 00099 20 CONTINUE 00100 * 00101 * Q := Q - I 00102 * 00103 DO 30 I = 1, N 00104 WORK( ( I-1 )*N+I ) = WORK( ( I-1 )*N+I ) - ONE 00105 30 CONTINUE 00106 * 00107 STZT02 = SLANGE( 'One-norm', N, N, WORK, N, RWORK ) / 00108 $ ( SLAMCH( 'Epsilon' )*REAL( MAX( M, N ) ) ) 00109 RETURN 00110 * 00111 * End of STZT02 00112 * 00113 END
1.7.3 
