strttp.c

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/* strttp.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 strttp_(char *uplo, integer *n, real *a, integer *lda, 
        real *ap, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2;

    /* Local variables */
    integer i__, j, k;
    extern logical lsame_(char *, char *);
    logical lower;
    extern /* Subroutine */ int xerbla_(char *, integer *);


/*  -- LAPACK routine (version 3.2) -- */
/*  -- Contributed by Fred Gustavson of the IBM Watson Research Center -- */
/*  --            and Julien Langou of the Univ. of Colorado Denver    -- */
/*  -- November 2008 -- */

/*  -- LAPACK is a software package provided by Univ. of Tennessee,    -- */
/*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */

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

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

/*  STRTTP copies a triangular matrix A from full format (TR) to standard */
/*  packed format (TP). */

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

/*  UPLO    (input) CHARACTER */
/*          = 'U':  A is upper triangular. */
/*          = 'L':  A is lower triangular. */

/*  N       (input) INTEGER */
/*          The order of the matrices AP and A.  N >= 0. */

/*  A       (input) REAL array, dimension (LDA,N) */
/*          On exit, the triangular 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. */

/*  LDA     (input) INTEGER */
/*          The leading dimension of the array A.  LDA >= max(1,N). */

/*  AP      (output) REAL array, dimension (N*(N+1)/2 */
/*          On exit, the upper or lower triangular matrix A, packed */
/*          columnwise in a linear array. The j-th column of A is stored */
/*          in the array AP as follows: */
/*          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; */
/*          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. */

/*  INFO    (output) INTEGER */
/*          = 0:  successful exit */
/*          < 0:  if INFO = -i, the i-th argument had an illegal value */

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

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

/*     Test the input parameters. */

    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --ap;

    /* Function Body */
    *info = 0;
    lower = lsame_(uplo, "L");
    if (! lower && ! lsame_(uplo, "U")) {
        *info = -1;
    } else if (*n < 0) {
        *info = -2;
    } else if (*lda < max(1,*n)) {
        *info = -4;
    }
    if (*info != 0) {
        i__1 = -(*info);
        xerbla_("STRTTP", &i__1);
        return 0;
    }

    if (lower) {
        k = 0;
        i__1 = *n;
        for (j = 1; j <= i__1; ++j) {
            i__2 = *n;
            for (i__ = j; i__ <= i__2; ++i__) {
                ++k;
                ap[k] = a[i__ + j * a_dim1];
            }
        }
    } else {
        k = 0;
        i__1 = *n;
        for (j = 1; j <= i__1; ++j) {
            i__2 = j;
            for (i__ = 1; i__ <= i__2; ++i__) {
                ++k;
                ap[k] = a[i__ + j * a_dim1];
            }
        }
    }

    return 0;

/*     End of STRTTP */

} /* strttp_ */