/*  -- translated by f2c (version 19940927).

   You must link the resulting object file with the libraries:

	-lf2c -lm   (in that order)

*/

#include "f2c.h"

doublereal slatm2_(integer *m, integer *n, integer *i, integer *j, integer *

	kl, integer *ku, integer *idist, integer *iseed, real *d, integer *

	igrade, real *dl, real *dr, integer *ipvtng, integer *iwork, real *

	sparse)

{

    /* System generated locals */

    real ret_val;

    /* Local variables */

    static integer isub, jsub;

    static real temp;

    extern doublereal slaran_(integer *), slarnd_(integer *, integer *);

/*  -- LAPACK auxiliary test routine (version 2.0) --   

       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   

       Courant Institute, Argonne National Lab, and Rice University   

       February 29, 1992   

    Purpose   

    =======   

       SLATM2 returns the (I,J) entry of a random matrix of dimension   

       (M, N) described by the other paramters. It is called by the   

       SLATMR routine in order to build random test matrices. No error   

       checking on parameters is done, because this routine is called in 

       a tight loop by SLATMR which has already checked the parameters.   

       Use of SLATM2 differs from SLATM3 in the order in which the random 

       number generator is called to fill in random matrix entries.   

       With SLATM2, the generator is called to fill in the pivoted matrix 

       columnwise. With SLATM3, the generator is called to fill in the   

       matrix columnwise, after which it is pivoted. Thus, SLATM3 can   

       be used to construct random matrices which differ only in their   

       order of rows and/or columns. SLATM2 is used to construct band   

       matrices while avoiding calling the random number generator for   

       entries outside the band (and therefore generating random numbers 

       The matrix whose (I,J) entry is returned is constructed as   

       follows (this routine only computes one entry):   

         If I is outside (1..M) or J is outside (1..N), return zero   

            (this is convenient for generating matrices in band format). 

         Generate a matrix A with random entries of distribution IDIST.   

         Set the diagonal to D.   

         Grade the matrix, if desired, from the left (by DL) and/or   

            from the right (by DR or DL) as specified by IGRADE.   

         Permute, if desired, the rows and/or columns as specified by   

            IPVTNG and IWORK.   

         Band the matrix to have lower bandwidth KL and upper   

            bandwidth KU.   

         Set random entries to zero as specified by SPARSE.   

    Arguments   

    =========   

    M      - INTEGER   

             Number of rows of matrix. Not modified.   

    N      - INTEGER   

             Number of columns of matrix. Not modified.   

    I      - INTEGER   

             Row of entry to be returned. Not modified.   

    J      - INTEGER   

             Column of entry to be returned. Not modified.   

    KL     - INTEGER   

             Lower bandwidth. Not modified.   

    KU     - INTEGER   

             Upper bandwidth. Not modified.   

    IDIST  - INTEGER   

             On entry, IDIST specifies the type of distribution to be   

             used to generate a random matrix .   

             1 => UNIFORM( 0, 1 )   

             2 => UNIFORM( -1, 1 )   

             3 => NORMAL( 0, 1 )   

             Not modified.   

    ISEED  - INTEGER array of dimension ( 4 )   

             Seed for random number generator.   

             Changed on exit.   

    D      - REAL array of dimension ( MIN( I , J ) )   

             Diagonal entries of matrix. Not modified.   

    IGRADE - INTEGER   

             Specifies grading of matrix as follows:   

             0  => no grading   

             1  => matrix premultiplied by diag( DL )   

             2  => matrix postmultiplied by diag( DR )   

             3  => matrix premultiplied by diag( DL ) and   

                           postmultiplied by diag( DR )   

             4  => matrix premultiplied by diag( DL ) and   

                           postmultiplied by inv( diag( DL ) )   

             5  => matrix premultiplied by diag( DL ) and   

                           postmultiplied by diag( DL )   

             Not modified.   

    DL     - REAL array ( I or J, as appropriate )   

             Left scale factors for grading matrix.  Not modified.   

    DR     - REAL array ( I or J, as appropriate )   

             Right scale factors for grading matrix.  Not modified.   

    IPVTNG - INTEGER   

             On entry specifies pivoting permutations as follows:   

             0 => none.   

             1 => row pivoting.   

             2 => column pivoting.   

             3 => full pivoting, i.e., on both sides.   

             Not modified.   

    IWORK  - INTEGER array ( I or J, as appropriate )   

             This array specifies the permutation used. The   

             row (or column) in position K was originally in   

             position IWORK( K ).   

             This differs from IWORK for SLATM3. Not modified.   

    SPARSE - REAL    between 0. and 1.   

             On entry specifies the sparsity of the matrix   

             if sparse matix is to be generated.   

             SPARSE should lie between 0 and 1.   

             A uniform ( 0, 1 ) random number x is generated and   

             compared to SPARSE; if x is larger the matrix entry   

             is unchanged and if x is smaller the entry is set   

             to zero. Thus on the average a fraction SPARSE of the   

             entries will be set to zero.   

             Not modified.   

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

   -----------------------------------------------------------------------

       Check for I and J in range   

       Parameter adjustments */

    --iwork;

    --dr;

    --dl;

    --d;

    --iseed;

    /* Function Body */

    if (*i < 1 || *i > *m || *j < 1 || *j > *n) {

	ret_val = 0.f;

	return ret_val;

    }

/*     Check for banding */

    if (*j > *i + *ku || *j < *i - *kl) {

	ret_val = 0.f;

	return ret_val;

    }

/*     Check for sparsity */

    if (*sparse > 0.f) {

	if (slaran_(&iseed[1]) < *sparse) {

	    ret_val = 0.f;

	    return ret_val;

	}

    }

/*     Compute subscripts depending on IPVTNG */

    if (*ipvtng == 0) {

	isub = *i;

	jsub = *j;

    } else if (*ipvtng == 1) {

	isub = iwork[*i];

	jsub = *j;

    } else if (*ipvtng == 2) {

	isub = *i;

	jsub = iwork[*j];

    } else if (*ipvtng == 3) {

	isub = iwork[*i];

	jsub = iwork[*j];

    }

/*     Compute entry and grade it according to IGRADE */

    if (isub == jsub) {

	temp = d[isub];

    } else {

	temp = slarnd_(idist, &iseed[1]);

    }

    if (*igrade == 1) {

	temp *= dl[isub];

    } else if (*igrade == 2) {

	temp *= dr[jsub];

    } else if (*igrade == 3) {

	temp = temp * dl[isub] * dr[jsub];

    } else if (*igrade == 4 && isub != jsub) {

	temp = temp * dl[isub] / dl[jsub];

    } else if (*igrade == 5) {

	temp = temp * dl[isub] * dl[jsub];

    }

    ret_val = temp;

    return ret_val;

/*     End of SLATM2 */

} /* slatm2_ */