Annotation of rpl/lapack/lapack/dlamch.f, revision 1.22
1.10 bertrand 1: *> \brief \b DLAMCH
2: *
3: * =========== DOCUMENTATION ===========
4: *
1.19 bertrand 5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
1.10 bertrand 7: *
8: * Definition:
9: * ===========
10: *
11: * DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
1.19 bertrand 12: *
1.22 ! bertrand 13: * .. Scalar Arguments ..
! 14: * CHARACTER CMACH
! 15: * ..
! 16: *
1.10 bertrand 17: *
18: *> \par Purpose:
19: * =============
20: *>
21: *> \verbatim
22: *>
23: *> DLAMCH determines double precision machine parameters.
24: *> \endverbatim
25: *
26: * Arguments:
27: * ==========
28: *
29: *> \param[in] CMACH
30: *> \verbatim
1.22 ! bertrand 31: *> CMACH is CHARACTER*1
1.10 bertrand 32: *> Specifies the value to be returned by DLAMCH:
33: *> = 'E' or 'e', DLAMCH := eps
34: *> = 'S' or 's , DLAMCH := sfmin
35: *> = 'B' or 'b', DLAMCH := base
36: *> = 'P' or 'p', DLAMCH := eps*base
37: *> = 'N' or 'n', DLAMCH := t
38: *> = 'R' or 'r', DLAMCH := rnd
39: *> = 'M' or 'm', DLAMCH := emin
40: *> = 'U' or 'u', DLAMCH := rmin
41: *> = 'L' or 'l', DLAMCH := emax
42: *> = 'O' or 'o', DLAMCH := rmax
43: *> where
44: *> eps = relative machine precision
45: *> sfmin = safe minimum, such that 1/sfmin does not overflow
46: *> base = base of the machine
47: *> prec = eps*base
48: *> t = number of (base) digits in the mantissa
49: *> rnd = 1.0 when rounding occurs in addition, 0.0 otherwise
50: *> emin = minimum exponent before (gradual) underflow
51: *> rmin = underflow threshold - base**(emin-1)
52: *> emax = largest exponent before overflow
53: *> rmax = overflow threshold - (base**emax)*(1-eps)
54: *> \endverbatim
55: *
56: * Authors:
57: * ========
58: *
1.19 bertrand 59: *> \author Univ. of Tennessee
60: *> \author Univ. of California Berkeley
61: *> \author Univ. of Colorado Denver
62: *> \author NAG Ltd.
1.10 bertrand 63: *
1.19 bertrand 64: *> \date December 2016
1.10 bertrand 65: *
66: *> \ingroup auxOTHERauxiliary
67: *
68: * =====================================================================
1.1 bertrand 69: DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
70: *
1.19 bertrand 71: * -- LAPACK auxiliary routine (version 3.7.0) --
1.7 bertrand 72: * -- LAPACK is a software package provided by Univ. of Tennessee, --
73: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.19 bertrand 74: * December 2016
1.1 bertrand 75: *
76: * .. Scalar Arguments ..
77: CHARACTER CMACH
78: * ..
79: *
80: * =====================================================================
81: *
82: * .. Parameters ..
83: DOUBLE PRECISION ONE, ZERO
84: PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 )
85: * ..
86: * .. Local Scalars ..
1.7 bertrand 87: DOUBLE PRECISION RND, EPS, SFMIN, SMALL, RMACH
1.1 bertrand 88: * ..
89: * .. External Functions ..
90: LOGICAL LSAME
91: EXTERNAL LSAME
92: * ..
1.7 bertrand 93: * .. Intrinsic Functions ..
94: INTRINSIC DIGITS, EPSILON, HUGE, MAXEXPONENT,
95: $ MINEXPONENT, RADIX, TINY
1.1 bertrand 96: * ..
97: * .. Executable Statements ..
98: *
1.7 bertrand 99: *
100: * Assume rounding, not chopping. Always.
101: *
102: RND = ONE
103: *
104: IF( ONE.EQ.RND ) THEN
105: EPS = EPSILON(ZERO) * 0.5
106: ELSE
107: EPS = EPSILON(ZERO)
108: END IF
109: *
110: IF( LSAME( CMACH, 'E' ) ) THEN
111: RMACH = EPS
112: ELSE IF( LSAME( CMACH, 'S' ) ) THEN
113: SFMIN = TINY(ZERO)
114: SMALL = ONE / HUGE(ZERO)
1.1 bertrand 115: IF( SMALL.GE.SFMIN ) THEN
116: *
117: * Use SMALL plus a bit, to avoid the possibility of rounding
118: * causing overflow when computing 1/sfmin.
119: *
120: SFMIN = SMALL*( ONE+EPS )
121: END IF
122: RMACH = SFMIN
123: ELSE IF( LSAME( CMACH, 'B' ) ) THEN
1.7 bertrand 124: RMACH = RADIX(ZERO)
1.1 bertrand 125: ELSE IF( LSAME( CMACH, 'P' ) ) THEN
1.7 bertrand 126: RMACH = EPS * RADIX(ZERO)
1.1 bertrand 127: ELSE IF( LSAME( CMACH, 'N' ) ) THEN
1.7 bertrand 128: RMACH = DIGITS(ZERO)
1.1 bertrand 129: ELSE IF( LSAME( CMACH, 'R' ) ) THEN
130: RMACH = RND
131: ELSE IF( LSAME( CMACH, 'M' ) ) THEN
1.7 bertrand 132: RMACH = MINEXPONENT(ZERO)
1.1 bertrand 133: ELSE IF( LSAME( CMACH, 'U' ) ) THEN
1.7 bertrand 134: RMACH = tiny(zero)
1.1 bertrand 135: ELSE IF( LSAME( CMACH, 'L' ) ) THEN
1.7 bertrand 136: RMACH = MAXEXPONENT(ZERO)
1.1 bertrand 137: ELSE IF( LSAME( CMACH, 'O' ) ) THEN
1.7 bertrand 138: RMACH = HUGE(ZERO)
139: ELSE
140: RMACH = ZERO
1.1 bertrand 141: END IF
142: *
143: DLAMCH = RMACH
144: RETURN
145: *
146: * End of DLAMCH
147: *
148: END
149: ************************************************************************
1.10 bertrand 150: *> \brief \b DLAMC3
151: *> \details
152: *> \b Purpose:
153: *> \verbatim
154: *> DLAMC3 is intended to force A and B to be stored prior to doing
155: *> the addition of A and B , for use in situations where optimizers
156: *> might hold one of these in a register.
157: *> \endverbatim
158: *> \author LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..
1.19 bertrand 159: *> \date December 2016
1.10 bertrand 160: *> \ingroup auxOTHERauxiliary
161: *>
162: *> \param[in] A
163: *> \verbatim
164: *> A is a DOUBLE PRECISION
165: *> \endverbatim
166: *>
167: *> \param[in] B
168: *> \verbatim
169: *> B is a DOUBLE PRECISION
170: *> The values A and B.
171: *> \endverbatim
172: *>
1.1 bertrand 173: DOUBLE PRECISION FUNCTION DLAMC3( A, B )
174: *
1.19 bertrand 175: * -- LAPACK auxiliary routine (version 3.7.0) --
1.1 bertrand 176: * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
1.7 bertrand 177: * November 2010
1.1 bertrand 178: *
179: * .. Scalar Arguments ..
180: DOUBLE PRECISION A, B
181: * ..
182: * =====================================================================
183: *
184: * .. Executable Statements ..
185: *
186: DLAMC3 = A + B
187: *
188: RETURN
189: *
190: * End of DLAMC3
191: *
192: END
193: *
194: ************************************************************************
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