LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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slamch.f
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1*> \brief \b SLAMCH
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 SLAMCH( CMACH )
12*
13* .. Scalar Arguments ..
14* CHARACTER CMACH
15* ..
16*
17*
18*> \par Purpose:
19* =============
20*>
21*> \verbatim
22*>
23*> SLAMCH determines single precision machine parameters.
24*> \endverbatim
25*
26* Arguments:
27* ==========
28*
29*> \param[in] CMACH
30*> \verbatim
31*> CMACH is CHARACTER*1
32*> Specifies the value to be returned by SLAMCH:
33*> = 'E' or 'e', SLAMCH := eps
34*> = 'S' or 's , SLAMCH := sfmin
35*> = 'B' or 'b', SLAMCH := base
36*> = 'P' or 'p', SLAMCH := eps*base
37*> = 'N' or 'n', SLAMCH := t
38*> = 'R' or 'r', SLAMCH := rnd
39*> = 'M' or 'm', SLAMCH := emin
40*> = 'U' or 'u', SLAMCH := rmin
41*> = 'L' or 'l', SLAMCH := emax
42*> = 'O' or 'o', SLAMCH := 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*
59*> \author Univ. of Tennessee
60*> \author Univ. of California Berkeley
61*> \author Univ. of Colorado Denver
62*> \author NAG Ltd.
63*
64*> \ingroup lamch
65*
66* =====================================================================
67 REAL function slamch( cmach )
68*
69* -- LAPACK auxiliary routine --
70* -- LAPACK is a software package provided by Univ. of Tennessee, --
71* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
72*
73* .. Scalar Arguments ..
74 CHARACTER cmach
75* ..
76*
77* =====================================================================
78*
79* .. Parameters ..
80 REAL one, zero
81 parameter( one = 1.0e+0, zero = 0.0e+0 )
82* ..
83* .. Local Scalars ..
84 REAL rnd, eps, sfmin, small, rmach
85* ..
86* .. External Functions ..
87 LOGICAL lsame
88 EXTERNAL lsame
89* ..
90* .. Intrinsic Functions ..
91 INTRINSIC digits, epsilon, huge, maxexponent,
93* ..
94* .. Executable Statements ..
95*
96*
97* Assume rounding, not chopping. Always.
98*
99 rnd = one
100*
101 IF( one.EQ.rnd ) THEN
102 eps = epsilon(zero) * 0.5
103 ELSE
104 eps = epsilon(zero)
105 END IF
106*
107 IF( lsame( cmach, 'E' ) ) THEN
108 rmach = eps
109 ELSE IF( lsame( cmach, 'S' ) ) THEN
110 sfmin = tiny(zero)
111 small = one / huge(zero)
112 IF( small.GE.sfmin ) THEN
113*
114* Use SMALL plus a bit, to avoid the possibility of rounding
115* causing overflow when computing 1/sfmin.
116*
117 sfmin = small*( one+eps )
118 END IF
119 rmach = sfmin
120 ELSE IF( lsame( cmach, 'B' ) ) THEN
122 ELSE IF( lsame( cmach, 'P' ) ) THEN
123 rmach = eps * radix(zero)
124 ELSE IF( lsame( cmach, 'N' ) ) THEN
125 rmach = digits(zero)
126 ELSE IF( lsame( cmach, 'R' ) ) THEN
127 rmach = rnd
128 ELSE IF( lsame( cmach, 'M' ) ) THEN
129 rmach = minexponent(zero)
130 ELSE IF( lsame( cmach, 'U' ) ) THEN
131 rmach = tiny(zero)
132 ELSE IF( lsame( cmach, 'L' ) ) THEN
133 rmach = maxexponent(zero)
134 ELSE IF( lsame( cmach, 'O' ) ) THEN
135 rmach = huge(zero)
136 ELSE
137 rmach = zero
138 END IF
139*
140 slamch = rmach
141 RETURN
142*
143* End of SLAMCH
144*
145 END
146
147************************************************************************
148*> \brief \b SLAMC3
149*> \details
150*> \b Purpose:
151*> \verbatim
152*> SLAMC3 is intended to force A and B to be stored prior to doing
153*> the addition of A and B , for use in situations where optimizers
154*> might hold one of these in a register.
155*> \endverbatim
156*> \author LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..
157*>
158*> \ingroup lamc3
159*>
160*> \param[in] A
161*> \verbatim
162*> \endverbatim
163*>
164*> \param[in] B
165*> \verbatim
166*> The values A and B.
167*> \endverbatim
168*>
169*
170 REAL function slamc3( a, b )
171*
172* -- LAPACK auxiliary routine --
173* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
174*
175* .. Scalar Arguments ..
176 REAL a, b
177* ..
178* =====================================================================
179*
180* .. Executable Statements ..
181*
182 slamc3 = a + b
183*
184 RETURN
185*
186* End of SLAMC3
187*
188 END
189*
190************************************************************************
real function slamc3(a, b)
SLAMC3
Definition slamch.f:171
real function slamch(cmach)
SLAMCH
Definition slamch.f:68
logical function lsame(ca, cb)
LSAME
Definition lsame.f:48