1 /* ./src_f77/spotrf.f -- translated by f2c (version 20030320).
2 You must link the resulting object file with the libraries:
3 -lf2c -lm (in that order)
4 */
5
6 #include <punc/vf2c.h>
7
8 /* Table of constant values */
9
10 static integer c__1 = 1;
11 static integer c_n1 = -1;
12 static real c_b13 = -1.f;
13 static real c_b14 = 1.f;
14
spotrf_(char * uplo,integer * n,real * a,integer * lda,integer * info,ftnlen uplo_len)15 /* Subroutine */ int spotrf_(char *uplo, integer *n, real *a, integer *lda,
16 integer *info, ftnlen uplo_len)
17 {
18 /* System generated locals */
19 integer a_dim1, a_offset, i__1, i__2, i__3, i__4;
20
21 /* Local variables */
22 static integer j, jb, nb;
23 extern logical lsame_(char *, char *, ftnlen, ftnlen);
24 extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *,
25 integer *, real *, real *, integer *, real *, integer *, real *,
26 real *, integer *, ftnlen, ftnlen);
27 static logical upper;
28 extern /* Subroutine */ int strsm_(char *, char *, char *, char *,
29 integer *, integer *, real *, real *, integer *, real *, integer *
30 , ftnlen, ftnlen, ftnlen, ftnlen), ssyrk_(char *, char *, integer
31 *, integer *, real *, real *, integer *, real *, real *, integer *
32 , ftnlen, ftnlen), spotf2_(char *, integer *, real *, integer *,
33 integer *, ftnlen), xerbla_(char *, integer *, ftnlen);
34 extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
35 integer *, integer *, ftnlen, ftnlen);
36
37
38 /* -- LAPACK routine (version 3.0) -- */
39 /* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
40 /* Courant Institute, Argonne National Lab, and Rice University */
41 /* March 31, 1993 */
42
43 /* .. Scalar Arguments .. */
44 /* .. */
45 /* .. Array Arguments .. */
46 /* .. */
47
48 /* Purpose */
49 /* ======= */
50
51 /* SPOTRF computes the Cholesky factorization of a real symmetric */
52 /* positive definite matrix A. */
53
54 /* The factorization has the form */
55 /* A = U**T * U, if UPLO = 'U', or */
56 /* A = L * L**T, if UPLO = 'L', */
57 /* where U is an upper triangular matrix and L is lower triangular. */
58
59 /* This is the block version of the algorithm, calling Level 3 BLAS. */
60
61 /* Arguments */
62 /* ========= */
63
64 /* UPLO (input) CHARACTER*1 */
65 /* = 'U': Upper triangle of A is stored; */
66 /* = 'L': Lower triangle of A is stored. */
67
68 /* N (input) INTEGER */
69 /* The order of the matrix A. N >= 0. */
70
71 /* A (input/output) REAL array, dimension (LDA,N) */
72 /* On entry, the symmetric matrix A. If UPLO = 'U', the leading */
73 /* N-by-N upper triangular part of A contains the upper */
74 /* triangular part of the matrix A, and the strictly lower */
75 /* triangular part of A is not referenced. If UPLO = 'L', the */
76 /* leading N-by-N lower triangular part of A contains the lower */
77 /* triangular part of the matrix A, and the strictly upper */
78 /* triangular part of A is not referenced. */
79
80 /* On exit, if INFO = 0, the factor U or L from the Cholesky */
81 /* factorization A = U**T*U or A = L*L**T. */
82
83 /* LDA (input) INTEGER */
84 /* The leading dimension of the array A. LDA >= max(1,N). */
85
86 /* INFO (output) INTEGER */
87 /* = 0: successful exit */
88 /* < 0: if INFO = -i, the i-th argument had an illegal value */
89 /* > 0: if INFO = i, the leading minor of order i is not */
90 /* positive definite, and the factorization could not be */
91 /* completed. */
92
93 /* ===================================================================== */
94
95 /* .. Parameters .. */
96 /* .. */
97 /* .. Local Scalars .. */
98 /* .. */
99 /* .. External Functions .. */
100 /* .. */
101 /* .. External Subroutines .. */
102 /* .. */
103 /* .. Intrinsic Functions .. */
104 /* .. */
105 /* .. Executable Statements .. */
106
107 /* Test the input parameters. */
108
109 /* Parameter adjustments */
110 a_dim1 = *lda;
111 a_offset = 1 + a_dim1;
112 a -= a_offset;
113
114 /* Function Body */
115 *info = 0;
116 upper = lsame_(uplo, "U", (ftnlen)1, (ftnlen)1);
117 if (! upper && ! lsame_(uplo, "L", (ftnlen)1, (ftnlen)1)) {
118 *info = -1;
119 } else if (*n < 0) {
120 *info = -2;
121 } else if (*lda < max(1,*n)) {
122 *info = -4;
123 }
124 if (*info != 0) {
125 i__1 = -(*info);
126 xerbla_("SPOTRF", &i__1, (ftnlen)6);
127 return 0;
128 }
129
130 /* Quick return if possible */
131
132 if (*n == 0) {
133 return 0;
134 }
135
136 /* Determine the block size for this environment. */
137
138 nb = ilaenv_(&c__1, "SPOTRF", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, (
139 ftnlen)1);
140 if (nb <= 1 || nb >= *n) {
141
142 /* Use unblocked code. */
143
144 spotf2_(uplo, n, &a[a_offset], lda, info, (ftnlen)1);
145 } else {
146
147 /* Use blocked code. */
148
149 if (upper) {
150
151 /* Compute the Cholesky factorization A = U'*U. */
152
153 i__1 = *n;
154 i__2 = nb;
155 for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) {
156
157 /* Update and factorize the current diagonal block and test */
158 /* for non-positive-definiteness. */
159
160 /* Computing MIN */
161 i__3 = nb, i__4 = *n - j + 1;
162 jb = min(i__3,i__4);
163 i__3 = j - 1;
164 ssyrk_("Upper", "Transpose", &jb, &i__3, &c_b13, &a[j *
165 a_dim1 + 1], lda, &c_b14, &a[j + j * a_dim1], lda, (
166 ftnlen)5, (ftnlen)9);
167 spotf2_("Upper", &jb, &a[j + j * a_dim1], lda, info, (ftnlen)
168 5);
169 if (*info != 0) {
170 goto L30;
171 }
172 if (j + jb <= *n) {
173
174 /* Compute the current block row. */
175
176 i__3 = *n - j - jb + 1;
177 i__4 = j - 1;
178 sgemm_("Transpose", "No transpose", &jb, &i__3, &i__4, &
179 c_b13, &a[j * a_dim1 + 1], lda, &a[(j + jb) *
180 a_dim1 + 1], lda, &c_b14, &a[j + (j + jb) *
181 a_dim1], lda, (ftnlen)9, (ftnlen)12);
182 i__3 = *n - j - jb + 1;
183 strsm_("Left", "Upper", "Transpose", "Non-unit", &jb, &
184 i__3, &c_b14, &a[j + j * a_dim1], lda, &a[j + (j
185 + jb) * a_dim1], lda, (ftnlen)4, (ftnlen)5, (
186 ftnlen)9, (ftnlen)8);
187 }
188 /* L10: */
189 }
190
191 } else {
192
193 /* Compute the Cholesky factorization A = L*L'. */
194
195 i__2 = *n;
196 i__1 = nb;
197 for (j = 1; i__1 < 0 ? j >= i__2 : j <= i__2; j += i__1) {
198
199 /* Update and factorize the current diagonal block and test */
200 /* for non-positive-definiteness. */
201
202 /* Computing MIN */
203 i__3 = nb, i__4 = *n - j + 1;
204 jb = min(i__3,i__4);
205 i__3 = j - 1;
206 ssyrk_("Lower", "No transpose", &jb, &i__3, &c_b13, &a[j +
207 a_dim1], lda, &c_b14, &a[j + j * a_dim1], lda, (
208 ftnlen)5, (ftnlen)12);
209 spotf2_("Lower", &jb, &a[j + j * a_dim1], lda, info, (ftnlen)
210 5);
211 if (*info != 0) {
212 goto L30;
213 }
214 if (j + jb <= *n) {
215
216 /* Compute the current block column. */
217
218 i__3 = *n - j - jb + 1;
219 i__4 = j - 1;
220 sgemm_("No transpose", "Transpose", &i__3, &jb, &i__4, &
221 c_b13, &a[j + jb + a_dim1], lda, &a[j + a_dim1],
222 lda, &c_b14, &a[j + jb + j * a_dim1], lda, (
223 ftnlen)12, (ftnlen)9);
224 i__3 = *n - j - jb + 1;
225 strsm_("Right", "Lower", "Transpose", "Non-unit", &i__3, &
226 jb, &c_b14, &a[j + j * a_dim1], lda, &a[j + jb +
227 j * a_dim1], lda, (ftnlen)5, (ftnlen)5, (ftnlen)9,
228 (ftnlen)8);
229 }
230 /* L20: */
231 }
232 }
233 }
234 goto L40;
235
236 L30:
237 *info = *info + j - 1;
238
239 L40:
240 return 0;
241
242 /* End of SPOTRF */
243
244 } /* spotrf_ */
245
246