#include "blaswrap.h"
/* dtzt02.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"

/* Table of constant values */

static integer c__7 = 7;
static doublereal c_b5 = 0.;
static doublereal c_b6 = 1.;

doublereal dtzt02_(integer *m, integer *n, doublereal *af, integer *lda, 
	doublereal *tau, doublereal *work, integer *lwork)
{
    /* System generated locals */
    integer af_dim1, af_offset, i__1, i__2;
    doublereal ret_val;

    /* Local variables */
    static integer i__;
    static doublereal rwork[1];
    extern doublereal dlamch_(char *), dlange_(char *, integer *, 
	    integer *, doublereal *, integer *, doublereal *);
    extern /* Subroutine */ int dlaset_(char *, integer *, integer *, 
	    doublereal *, doublereal *, doublereal *, integer *), 
	    xerbla_(char *, integer *), dlatzm_(char *, integer *, 
	    integer *, doublereal *, integer *, doublereal *, doublereal *, 
	    doublereal *, integer *, doublereal *);


/*  -- LAPACK test routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    DTZT02 returns   
         || I - Q'*Q || / ( M * eps)   
    where the matrix Q is defined by the Householder transformations   
    generated by DTZRQF.   

    Arguments   
    =========   

    M       (input) INTEGER   
            The number of rows of the matrix AF.   

    N       (input) INTEGER   
            The number of columns of the matrix AF.   

    AF      (input) DOUBLE PRECISION array, dimension (LDA,N)   
            The output of DTZRQF.   

    LDA     (input) INTEGER   
            The leading dimension of the array AF.   

    TAU     (input) DOUBLE PRECISION array, dimension (M)   
            Details of the Householder transformations as returned by   
            DTZRQF.   

    WORK    (workspace) DOUBLE PRECISION array, dimension (LWORK)   

    LWORK   (input) INTEGER   
            length of WORK array. Must be >= N*N+N   

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


       Parameter adjustments */
    af_dim1 = *lda;
    af_offset = 1 + af_dim1;
    af -= af_offset;
    --tau;
    --work;

    /* Function Body */
    ret_val = 0.;

    if (*lwork < *n * *n + *n) {
	xerbla_("DTZT02", &c__7);
	return ret_val;
    }

/*     Quick return if possible */

    if (*m <= 0 || *n <= 0) {
	return ret_val;
    }

/*     Q := I */

    dlaset_("Full", n, n, &c_b5, &c_b6, &work[1], n);

/*     Q := P(1) * ... * P(m) * Q */

    for (i__ = *m; i__ >= 1; --i__) {
	i__1 = *n - *m + 1;
	dlatzm_("Left", &i__1, n, &af[i__ + (*m + 1) * af_dim1], lda, &tau[
		i__], &work[i__], &work[*m + 1], n, &work[*n * *n + 1]);
/* L10: */
    }

/*     Q := P(m) * ... * P(1) * Q */

    i__1 = *m;
    for (i__ = 1; i__ <= i__1; ++i__) {
	i__2 = *n - *m + 1;
	dlatzm_("Left", &i__2, n, &af[i__ + (*m + 1) * af_dim1], lda, &tau[
		i__], &work[i__], &work[*m + 1], n, &work[*n * *n + 1]);
/* L20: */
    }

/*     Q := Q - I */

    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
	work[(i__ - 1) * *n + i__] += -1.;
/* L30: */
    }

    ret_val = dlange_("One-norm", n, n, &work[1], n, rwork) / (
	    dlamch_("Epsilon") * (doublereal) max(*m,*n));
    return ret_val;

/*     End of DTZT02 */

} /* dtzt02_ */