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

/* Subroutine */ int zpptri_(char *uplo, integer *n, doublecomplex *ap, 
	integer *info)
{
/*  -- LAPACK routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    ZPPTRI computes the inverse of a complex Hermitian positive definite   
    matrix A using the Cholesky factorization A = U**H*U or A = L*L**H   
    computed by ZPPTRF.   

    Arguments   
    =========   

    UPLO    (input) CHARACTER*1   
            = 'U':  Upper triangular factor is stored in AP;   
            = 'L':  Lower triangular factor is stored in AP.   

    N       (input) INTEGER   
            The order of the matrix A.  N >= 0.   

    AP      (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)   
            On entry, the triangular factor U or L from the Cholesky   
            factorization A = U**H*U or A = L*L**H, packed columnwise as   
            a linear array.  The j-th column of U or L is stored in the   
            array AP as follows:   
            if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;   
            if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.   

            On exit, the upper or lower triangle of the (Hermitian)   
            inverse of A, overwriting the input factor U or L.   

    INFO    (output) INTEGER   
            = 0:  successful exit   
            < 0:  if INFO = -i, the i-th argument had an illegal value   
            > 0:  if INFO = i, the (i,i) element of the factor U or L is   
                  zero, and the inverse could not be computed.   

    =====================================================================   


       Test the input parameters.   

       Parameter adjustments */
    /* Table of constant values */
    static doublereal c_b8 = 1.;
    static integer c__1 = 1;
    
    /* System generated locals */
    integer i__1, i__2, i__3;
    doublereal d__1;
    doublecomplex z__1;
    /* Local variables */
    static integer j, jc, jj;
    static doublereal ajj;
    static integer jjn;
    extern /* Subroutine */ int zhpr_(char *, integer *, doublereal *, 
	    doublecomplex *, integer *, doublecomplex *);
    extern logical lsame_(char *, char *);
    extern /* Double Complex */ VOID zdotc_(doublecomplex *, integer *, 
	    doublecomplex *, integer *, doublecomplex *, integer *);
    static logical upper;
    extern /* Subroutine */ int ztpmv_(char *, char *, char *, integer *, 
	    doublecomplex *, doublecomplex *, integer *), xerbla_(char *, integer *), zdscal_(integer *, 
	    doublereal *, doublecomplex *, integer *), ztptri_(char *, char *,
	     integer *, doublecomplex *, integer *);


    --ap;

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

/*     Quick return if possible */

    if (*n == 0) {
	return 0;
    }

/*     Invert the triangular Cholesky factor U or L. */

    ztptri_(uplo, "Non-unit", n, &ap[1], info);
    if (*info > 0) {
	return 0;
    }
    if (upper) {

/*        Compute the product inv(U) * inv(U)'. */

	jj = 0;
	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    jc = jj + 1;
	    jj += j;
	    if (j > 1) {
		i__2 = j - 1;
		zhpr_("Upper", &i__2, &c_b8, &ap[jc], &c__1, &ap[1]);
	    }
	    i__2 = jj;
	    ajj = ap[i__2].r;
	    zdscal_(&j, &ajj, &ap[jc], &c__1);
/* L10: */
	}

    } else {

/*        Compute the product inv(L)' * inv(L). */

	jj = 1;
	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    jjn = jj + *n - j + 1;
	    i__2 = jj;
	    i__3 = *n - j + 1;
	    zdotc_(&z__1, &i__3, &ap[jj], &c__1, &ap[jj], &c__1);
	    d__1 = z__1.r;
	    ap[i__2].r = d__1, ap[i__2].i = 0.;
	    if (j < *n) {
		i__2 = *n - j;
		ztpmv_("Lower", "Conjugate transpose", "Non-unit", &i__2, &ap[
			jjn], &ap[jj + 1], &c__1);
	    }
	    jj = jjn;
/* L20: */
	}
    }

    return 0;

/*     End of ZPPTRI */

} /* zpptri_ */