#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int claqsy_(char *uplo, integer *n, complex *a, integer *lda, real *s, real *scond, real *amax, char *equed) { /* -- LAPACK auxiliary routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= CLAQSY equilibrates a symmetric matrix A using the scaling factors in the vector S. Arguments ========= UPLO (input) CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular = 'L': Lower triangular N (input) INTEGER The order of the matrix A. N >= 0. A (input/output) COMPLEX array, dimension (LDA,N) On entry, the symmetric matrix A. If UPLO = 'U', the leading n by n upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. On exit, if EQUED = 'Y', the equilibrated matrix: diag(S) * A * diag(S). LDA (input) INTEGER The leading dimension of the array A. LDA >= max(N,1). S (input) REAL array, dimension (N) The scale factors for A. SCOND (input) REAL Ratio of the smallest S(i) to the largest S(i). AMAX (input) REAL Absolute value of largest matrix entry. EQUED (output) CHARACTER*1 Specifies whether or not equilibration was done. = 'N': No equilibration. = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S). Internal Parameters =================== THRESH is a threshold value used to decide if scaling should be done based on the ratio of the scaling factors. If SCOND < THRESH, scaling is done. LARGE and SMALL are threshold values used to decide if scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, scaling is done. ===================================================================== Quick return if possible Parameter adjustments */ /* System generated locals */ integer a_dim1, a_offset, i__1, i__2, i__3, i__4; real r__1; complex q__1; /* Local variables */ static integer i__, j; static real cj, large; extern logical lsame_(char *, char *); static real small; extern doublereal slamch_(char *); a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --s; /* Function Body */ if (*n <= 0) { *(unsigned char *)equed = 'N'; return 0; } /* Initialize LARGE and SMALL. */ small = slamch_("Safe minimum") / slamch_("Precision"); large = 1.f / small; if (*scond >= .1f && *amax >= small && *amax <= large) { /* No equilibration */ *(unsigned char *)equed = 'N'; } else { /* Replace A by diag(S) * A * diag(S). */ if (lsame_(uplo, "U")) { /* Upper triangle of A is stored. */ i__1 = *n; for (j = 1; j <= i__1; ++j) { cj = s[j]; i__2 = j; for (i__ = 1; i__ <= i__2; ++i__) { i__3 = i__ + j * a_dim1; r__1 = cj * s[i__]; i__4 = i__ + j * a_dim1; q__1.r = r__1 * a[i__4].r, q__1.i = r__1 * a[i__4].i; a[i__3].r = q__1.r, a[i__3].i = q__1.i; /* L10: */ } /* L20: */ } } else { /* Lower triangle of A is stored. */ i__1 = *n; for (j = 1; j <= i__1; ++j) { cj = s[j]; i__2 = *n; for (i__ = j; i__ <= i__2; ++i__) { i__3 = i__ + j * a_dim1; r__1 = cj * s[i__]; i__4 = i__ + j * a_dim1; q__1.r = r__1 * a[i__4].r, q__1.i = r__1 * a[i__4].i; a[i__3].r = q__1.r, a[i__3].i = q__1.i; /* L30: */ } /* L40: */ } } *(unsigned char *)equed = 'Y'; } return 0; /* End of CLAQSY */ } /* claqsy_ */