/* -- translated by f2c (version 19940927).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
doublereal dlatm2_(integer *m, integer *n, integer *i, integer *j, integer *
kl, integer *ku, integer *idist, integer *iseed, doublereal *d,
integer *igrade, doublereal *dl, doublereal *dr, integer *ipvtng,
integer *iwork, doublereal *sparse)
{
/* System generated locals */
doublereal ret_val;
/* Local variables */
static integer isub, jsub;
static doublereal temp;
extern doublereal dlaran_(integer *), dlarnd_(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
=======
DLATM2 returns the (I,J) entry of a random matrix of dimension
(M, N) described by the other paramters. It is called by the
DLATMR 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 DLATMR which has already checked the parameters.
Use of DLATM2 differs from SLATM3 in the order in which the random
number generator is called to fill in random matrix entries.
With DLATM2, the generator is called to fill in the pivoted matrix
columnwise. With DLATM3, the generator is called to fill in the
matrix columnwise, after which it is pivoted. Thus, DLATM3 can
be used to construct random matrices which differ only in their
order of rows and/or columns. DLATM2 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 - DOUBLE PRECISION 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 - DOUBLE PRECISION array ( I or J, as appropriate )
Left scale factors for grading matrix. Not modified.
DR - DOUBLE PRECISION 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 DLATM3. Not modified.
SPARSE - DOUBLE PRECISION 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.;
return ret_val;
}
/* Check for banding */
if (*j > *i + *ku || *j < *i - *kl) {
ret_val = 0.;
return ret_val;
}
/* Check for sparsity */
if (*sparse > 0.) {
if (dlaran_(&iseed[1]) < *sparse) {
ret_val = 0.;
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 = dlarnd_(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 DLATM2 */
} /* dlatm2_ */