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259 lines
7.1 KiB
259 lines
7.1 KiB
/* sgetri.f -- translated by f2c (version 20061008). |
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You must link the resulting object file with libf2c: |
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on Microsoft Windows system, link with libf2c.lib; |
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm |
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or, if you install libf2c.a in a standard place, with -lf2c -lm |
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-- in that order, at the end of the command line, as in |
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cc *.o -lf2c -lm |
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., |
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http://www.netlib.org/f2c/libf2c.zip |
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*/ |
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#include "clapack.h" |
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/* Table of constant values */ |
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static integer c__1 = 1; |
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static integer c_n1 = -1; |
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static integer c__2 = 2; |
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static real c_b20 = -1.f; |
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static real c_b22 = 1.f; |
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/* Subroutine */ int sgetri_(integer *n, real *a, integer *lda, integer *ipiv, |
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real *work, integer *lwork, integer *info) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, i__1, i__2, i__3; |
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/* Local variables */ |
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integer i__, j, jb, nb, jj, jp, nn, iws, nbmin; |
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extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, |
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integer *, real *, real *, integer *, real *, integer *, real *, |
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real *, integer *), sgemv_(char *, integer *, |
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integer *, real *, real *, integer *, real *, integer *, real *, |
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real *, integer *), sswap_(integer *, real *, integer *, |
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real *, integer *), strsm_(char *, char *, char *, char *, |
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integer *, integer *, real *, real *, integer *, real *, integer * |
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), xerbla_(char *, integer *); |
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extern integer ilaenv_(integer *, char *, char *, integer *, integer *, |
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integer *, integer *); |
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integer ldwork, lwkopt; |
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logical lquery; |
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extern /* Subroutine */ int strtri_(char *, char *, integer *, real *, |
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integer *, integer *); |
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/* -- LAPACK routine (version 3.2) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* SGETRI computes the inverse of a matrix using the LU factorization */ |
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/* computed by SGETRF. */ |
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/* This method inverts U and then computes inv(A) by solving the system */ |
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/* inv(A)*L = inv(U) for inv(A). */ |
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/* Arguments */ |
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/* ========= */ |
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/* N (input) INTEGER */ |
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/* The order of the matrix A. N >= 0. */ |
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/* A (input/output) REAL array, dimension (LDA,N) */ |
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/* On entry, the factors L and U from the factorization */ |
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/* A = P*L*U as computed by SGETRF. */ |
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/* On exit, if INFO = 0, the inverse of the original matrix A. */ |
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/* LDA (input) INTEGER */ |
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/* The leading dimension of the array A. LDA >= max(1,N). */ |
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/* IPIV (input) INTEGER array, dimension (N) */ |
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/* The pivot indices from SGETRF; for 1<=i<=N, row i of the */ |
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/* matrix was interchanged with row IPIV(i). */ |
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/* WORK (workspace/output) REAL array, dimension (MAX(1,LWORK)) */ |
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/* On exit, if INFO=0, then WORK(1) returns the optimal LWORK. */ |
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/* LWORK (input) INTEGER */ |
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/* The dimension of the array WORK. LWORK >= max(1,N). */ |
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/* For optimal performance LWORK >= N*NB, where NB is */ |
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/* the optimal blocksize returned by ILAENV. */ |
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/* If LWORK = -1, then a workspace query is assumed; the routine */ |
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/* only calculates the optimal size of the WORK array, returns */ |
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/* this value as the first entry of the WORK array, and no error */ |
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/* message related to LWORK is issued by XERBLA. */ |
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/* INFO (output) INTEGER */ |
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/* = 0: successful exit */ |
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/* < 0: if INFO = -i, the i-th argument had an illegal value */ |
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/* > 0: if INFO = i, U(i,i) is exactly zero; the matrix is */ |
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/* singular and its inverse could not be computed. */ |
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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Test the input parameters. */ |
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/* Parameter adjustments */ |
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a_dim1 = *lda; |
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a_offset = 1 + a_dim1; |
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a -= a_offset; |
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--ipiv; |
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--work; |
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/* Function Body */ |
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*info = 0; |
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nb = ilaenv_(&c__1, "SGETRI", " ", n, &c_n1, &c_n1, &c_n1); |
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lwkopt = *n * nb; |
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work[1] = (real) lwkopt; |
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lquery = *lwork == -1; |
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if (*n < 0) { |
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*info = -1; |
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} else if (*lda < max(1,*n)) { |
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*info = -3; |
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} else if (*lwork < max(1,*n) && ! lquery) { |
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*info = -6; |
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} |
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if (*info != 0) { |
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i__1 = -(*info); |
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xerbla_("SGETRI", &i__1); |
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return 0; |
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} else if (lquery) { |
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return 0; |
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} |
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/* Quick return if possible */ |
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if (*n == 0) { |
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return 0; |
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} |
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/* Form inv(U). If INFO > 0 from STRTRI, then U is singular, */ |
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/* and the inverse is not computed. */ |
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strtri_("Upper", "Non-unit", n, &a[a_offset], lda, info); |
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if (*info > 0) { |
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return 0; |
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} |
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nbmin = 2; |
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ldwork = *n; |
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if (nb > 1 && nb < *n) { |
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/* Computing MAX */ |
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i__1 = ldwork * nb; |
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iws = max(i__1,1); |
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if (*lwork < iws) { |
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nb = *lwork / ldwork; |
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/* Computing MAX */ |
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i__1 = 2, i__2 = ilaenv_(&c__2, "SGETRI", " ", n, &c_n1, &c_n1, & |
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c_n1); |
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nbmin = max(i__1,i__2); |
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} |
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} else { |
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iws = *n; |
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} |
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/* Solve the equation inv(A)*L = inv(U) for inv(A). */ |
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if (nb < nbmin || nb >= *n) { |
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/* Use unblocked code. */ |
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for (j = *n; j >= 1; --j) { |
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/* Copy current column of L to WORK and replace with zeros. */ |
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i__1 = *n; |
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for (i__ = j + 1; i__ <= i__1; ++i__) { |
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work[i__] = a[i__ + j * a_dim1]; |
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a[i__ + j * a_dim1] = 0.f; |
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/* L10: */ |
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} |
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/* Compute current column of inv(A). */ |
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if (j < *n) { |
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i__1 = *n - j; |
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sgemv_("No transpose", n, &i__1, &c_b20, &a[(j + 1) * a_dim1 |
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+ 1], lda, &work[j + 1], &c__1, &c_b22, &a[j * a_dim1 |
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+ 1], &c__1); |
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} |
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/* L20: */ |
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} |
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} else { |
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/* Use blocked code. */ |
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nn = (*n - 1) / nb * nb + 1; |
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i__1 = -nb; |
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for (j = nn; i__1 < 0 ? j >= 1 : j <= 1; j += i__1) { |
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/* Computing MIN */ |
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i__2 = nb, i__3 = *n - j + 1; |
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jb = min(i__2,i__3); |
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/* Copy current block column of L to WORK and replace with */ |
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/* zeros. */ |
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i__2 = j + jb - 1; |
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for (jj = j; jj <= i__2; ++jj) { |
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i__3 = *n; |
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for (i__ = jj + 1; i__ <= i__3; ++i__) { |
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work[i__ + (jj - j) * ldwork] = a[i__ + jj * a_dim1]; |
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a[i__ + jj * a_dim1] = 0.f; |
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/* L30: */ |
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} |
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/* L40: */ |
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} |
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/* Compute current block column of inv(A). */ |
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if (j + jb <= *n) { |
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i__2 = *n - j - jb + 1; |
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sgemm_("No transpose", "No transpose", n, &jb, &i__2, &c_b20, |
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&a[(j + jb) * a_dim1 + 1], lda, &work[j + jb], & |
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ldwork, &c_b22, &a[j * a_dim1 + 1], lda); |
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} |
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strsm_("Right", "Lower", "No transpose", "Unit", n, &jb, &c_b22, & |
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work[j], &ldwork, &a[j * a_dim1 + 1], lda); |
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/* L50: */ |
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} |
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} |
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/* Apply column interchanges. */ |
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for (j = *n - 1; j >= 1; --j) { |
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jp = ipiv[j]; |
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if (jp != j) { |
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sswap_(n, &a[j * a_dim1 + 1], &c__1, &a[jp * a_dim1 + 1], &c__1); |
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} |
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/* L60: */ |
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} |
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work[1] = (real) iws; |
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return 0; |
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/* End of SGETRI */ |
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} /* sgetri_ */
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