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sget06.f 2.5 kB

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  1. *> \brief \b SGET06
  2. *
  3. * =========== DOCUMENTATION ===========
  4. *
  5. * Online html documentation available at
  6. * http://www.netlib.org/lapack/explore-html/
  7. *
  8. * Definition:
  9. * ===========
  10. *
  11. * REAL FUNCTION SGET06( RCOND, RCONDC )
  12. *
  13. * .. Scalar Arguments ..
  14. * REAL RCOND, RCONDC
  15. * ..
  16. *
  17. *
  18. *> \par Purpose:
  19. * =============
  20. *>
  21. *> \verbatim
  22. *>
  23. *> SGET06 computes a test ratio to compare two values for RCOND.
  24. *> \endverbatim
  25. *
  26. * Arguments:
  27. * ==========
  28. *
  29. *> \param[in] RCOND
  30. *> \verbatim
  31. *> RCOND is REAL
  32. *> The estimate of the reciprocal of the condition number of A,
  33. *> as computed by SGECON.
  34. *> \endverbatim
  35. *>
  36. *> \param[in] RCONDC
  37. *> \verbatim
  38. *> RCONDC is REAL
  39. *> The reciprocal of the condition number of A, computed as
  40. *> ( 1/norm(A) ) / norm(inv(A)).
  41. *> \endverbatim
  42. *
  43. * Authors:
  44. * ========
  45. *
  46. *> \author Univ. of Tennessee
  47. *> \author Univ. of California Berkeley
  48. *> \author Univ. of Colorado Denver
  49. *> \author NAG Ltd.
  50. *
  51. *> \date December 2016
  52. *
  53. *> \ingroup single_lin
  54. *
  55. * =====================================================================
  56. REAL FUNCTION SGET06( RCOND, RCONDC )
  57. *
  58. * -- LAPACK test routine (version 3.7.0) --
  59. * -- LAPACK is a software package provided by Univ. of Tennessee, --
  60. * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
  61. * December 2016
  62. *
  63. * .. Scalar Arguments ..
  64. REAL RCOND, RCONDC
  65. * ..
  66. *
  67. * =====================================================================
  68. *
  69. * .. Parameters ..
  70. REAL ZERO, ONE
  71. PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 )
  72. * ..
  73. * .. Local Scalars ..
  74. REAL EPS, RAT
  75. * ..
  76. * .. External Functions ..
  77. REAL SLAMCH
  78. EXTERNAL SLAMCH
  79. * ..
  80. * .. Intrinsic Functions ..
  81. INTRINSIC MAX, MIN
  82. * ..
  83. * .. Executable Statements ..
  84. *
  85. EPS = SLAMCH( 'Epsilon' )
  86. IF( RCOND.GT.ZERO ) THEN
  87. IF( RCONDC.GT.ZERO ) THEN
  88. RAT = MAX( RCOND, RCONDC ) / MIN( RCOND, RCONDC ) -
  89. $ ( ONE-EPS )
  90. ELSE
  91. RAT = RCOND / EPS
  92. END IF
  93. ELSE
  94. IF( RCONDC.GT.ZERO ) THEN
  95. RAT = RCONDC / EPS
  96. ELSE
  97. RAT = ZERO
  98. END IF
  99. END IF
  100. SGET06 = RAT
  101. RETURN
  102. *
  103. * End of SGET06
  104. *
  105. END