aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/clapack/slaqgb.c
blob: 1a4a6b0af6274b1949cab0877f970c14bd406b5c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
/* slaqgb.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
	on Microsoft Windows system, link with libf2c.lib;
	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
	or, if you install libf2c.a in a standard place, with -lf2c -lm
	-- in that order, at the end of the command line, as in
		cc *.o -lf2c -lm
	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

		http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"
#include "blaswrap.h"

/* Subroutine */ int slaqgb_(integer *m, integer *n, integer *kl, integer *ku, 
	 real *ab, integer *ldab, real *r__, real *c__, real *rowcnd, real *
	colcnd, real *amax, char *equed)
{
    /* System generated locals */
    integer ab_dim1, ab_offset, i__1, i__2, i__3, i__4, i__5, i__6;

    /* Local variables */
    integer i__, j;
    real cj, large, small;
    extern doublereal slamch_(char *);


/*  -- LAPACK auxiliary routine (version 3.2) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  SLAQGB equilibrates a general M by N band matrix A with KL */
/*  subdiagonals and KU superdiagonals using the row and scaling factors */
/*  in the vectors R and C. */

/*  Arguments */
/*  ========= */

/*  M       (input) INTEGER */
/*          The number of rows of the matrix A.  M >= 0. */

/*  N       (input) INTEGER */
/*          The number of columns of the matrix A.  N >= 0. */

/*  KL      (input) INTEGER */
/*          The number of subdiagonals within the band of A.  KL >= 0. */

/*  KU      (input) INTEGER */
/*          The number of superdiagonals within the band of A.  KU >= 0. */

/*  AB      (input/output) REAL array, dimension (LDAB,N) */
/*          On entry, the matrix A in band storage, in rows 1 to KL+KU+1. */
/*          The j-th column of A is stored in the j-th column of the */
/*          array AB as follows: */
/*          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl) */

/*          On exit, the equilibrated matrix, in the same storage format */
/*          as A.  See EQUED for the form of the equilibrated matrix. */

/*  LDAB    (input) INTEGER */
/*          The leading dimension of the array AB.  LDA >= KL+KU+1. */

/*  R       (input) REAL array, dimension (M) */
/*          The row scale factors for A. */

/*  C       (input) REAL array, dimension (N) */
/*          The column scale factors for A. */

/*  ROWCND  (input) REAL */
/*          Ratio of the smallest R(i) to the largest R(i). */

/*  COLCND  (input) REAL */
/*          Ratio of the smallest C(i) to the largest C(i). */

/*  AMAX    (input) REAL */
/*          Absolute value of largest matrix entry. */

/*  EQUED   (output) CHARACTER*1 */
/*          Specifies the form of equilibration that was done. */
/*          = 'N':  No equilibration */
/*          = 'R':  Row equilibration, i.e., A has been premultiplied by */
/*                  diag(R). */
/*          = 'C':  Column equilibration, i.e., A has been postmultiplied */
/*                  by diag(C). */
/*          = 'B':  Both row and column equilibration, i.e., A has been */
/*                  replaced by diag(R) * A * diag(C). */

/*  Internal Parameters */
/*  =================== */

/*  THRESH is a threshold value used to decide if row or column scaling */
/*  should be done based on the ratio of the row or column scaling */
/*  factors.  If ROWCND < THRESH, row scaling is done, and if */
/*  COLCND < THRESH, column scaling is done. */

/*  LARGE and SMALL are threshold values used to decide if row scaling */
/*  should be done based on the absolute size of the largest matrix */
/*  element.  If AMAX > LARGE or AMAX < SMALL, row scaling is done. */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. Executable Statements .. */

/*     Quick return if possible */

    /* Parameter adjustments */
    ab_dim1 = *ldab;
    ab_offset = 1 + ab_dim1;
    ab -= ab_offset;
    --r__;
    --c__;

    /* Function Body */
    if (*m <= 0 || *n <= 0) {
	*(unsigned char *)equed = 'N';
	return 0;
    }

/*     Initialize LARGE and SMALL. */

    small = slamch_("Safe minimum") / slamch_("Precision");
    large = 1.f / small;

    if (*rowcnd >= .1f && *amax >= small && *amax <= large) {

/*        No row scaling */

	if (*colcnd >= .1f) {

/*           No column scaling */

	    *(unsigned char *)equed = 'N';
	} else {

/*           Column scaling */

	    i__1 = *n;
	    for (j = 1; j <= i__1; ++j) {
		cj = c__[j];
/* Computing MAX */
		i__2 = 1, i__3 = j - *ku;
/* Computing MIN */
		i__5 = *m, i__6 = j + *kl;
		i__4 = min(i__5,i__6);
		for (i__ = max(i__2,i__3); i__ <= i__4; ++i__) {
		    ab[*ku + 1 + i__ - j + j * ab_dim1] = cj * ab[*ku + 1 + 
			    i__ - j + j * ab_dim1];
/* L10: */
		}
/* L20: */
	    }
	    *(unsigned char *)equed = 'C';
	}
    } else if (*colcnd >= .1f) {

/*        Row scaling, no column scaling */

	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
/* Computing MAX */
	    i__4 = 1, i__2 = j - *ku;
/* Computing MIN */
	    i__5 = *m, i__6 = j + *kl;
	    i__3 = min(i__5,i__6);
	    for (i__ = max(i__4,i__2); i__ <= i__3; ++i__) {
		ab[*ku + 1 + i__ - j + j * ab_dim1] = r__[i__] * ab[*ku + 1 + 
			i__ - j + j * ab_dim1];
/* L30: */
	    }
/* L40: */
	}
	*(unsigned char *)equed = 'R';
    } else {

/*        Row and column scaling */

	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    cj = c__[j];
/* Computing MAX */
	    i__3 = 1, i__4 = j - *ku;
/* Computing MIN */
	    i__5 = *m, i__6 = j + *kl;
	    i__2 = min(i__5,i__6);
	    for (i__ = max(i__3,i__4); i__ <= i__2; ++i__) {
		ab[*ku + 1 + i__ - j + j * ab_dim1] = cj * r__[i__] * ab[*ku 
			+ 1 + i__ - j + j * ab_dim1];
/* L50: */
	    }
/* L60: */
	}
	*(unsigned char *)equed = 'B';
    }

    return 0;

/*     End of SLAQGB */

} /* slaqgb_ */