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DOUBLE PRECISION FUNCTION DLATM2( M, N, I, J, KL, KU, IDIST,
$ ISEED, D, IGRADE, DL, DR, IPVTNG, IWORK, SPARSE ) * * -- LAPACK auxiliary test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * June 2010 * * .. Scalar Arguments .. * INTEGER I, IDIST, IGRADE, IPVTNG, J, KL, KU, M, N DOUBLE PRECISION SPARSE * .. * * .. Array Arguments .. * INTEGER ISEED( 4 ), IWORK( * ) DOUBLE PRECISION D( * ), DL( * ), DR( * ) * .. * * 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 (input) INTEGER * Number of rows of matrix. Not modified. * * N (input) INTEGER * Number of columns of matrix. Not modified. * * I (input) INTEGER * Row of entry to be returned. Not modified. * * J (input) INTEGER * Column of entry to be returned. Not modified. * * KL (input) INTEGER * Lower bandwidth. Not modified. * * KU (input) INTEGER * Upper bandwidth. Not modified. * * IDIST (input) 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 (input/output) INTEGER array of dimension ( 4 ) * Seed for random number generator. * Changed on exit. * * D (input) DOUBLE PRECISION array of dimension ( MIN( I , J ) ) * Diagonal entries of matrix. Not modified. * * IGRADE (input) 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 (input) DOUBLE PRECISION array ( I or J, as appropriate ) * Left scale factors for grading matrix. Not modified. * * DR (input) DOUBLE PRECISION array ( I or J, as appropriate ) * Right scale factors for grading matrix. Not modified. * * IPVTNG (input) 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 (workspace) 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 (input) 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. * * ===================================================================== * * .. Parameters .. * DOUBLE PRECISION ZERO PARAMETER ( ZERO = 0.0D0 ) * .. * * .. Local Scalars .. * INTEGER ISUB, JSUB DOUBLE PRECISION TEMP * .. * * .. External Functions .. * DOUBLE PRECISION DLARAN, DLARND EXTERNAL DLARAN, DLARND * .. * *----------------------------------------------------------------------- * * .. Executable Statements .. * * * Check for I and J in range * IF( I.LT.1 .OR. I.GT.M .OR. J.LT.1 .OR. J.GT.N ) THEN DLATM2 = ZERO RETURN END IF * * Check for banding * IF( J.GT.I+KU .OR. J.LT.I-KL ) THEN DLATM2 = ZERO RETURN END IF * * Check for sparsity * IF( SPARSE.GT.ZERO ) THEN IF( DLARAN( ISEED ).LT.SPARSE ) THEN DLATM2 = ZERO RETURN END IF END IF * * Compute subscripts depending on IPVTNG * IF( IPVTNG.EQ.0 ) THEN ISUB = I JSUB = J ELSE IF( IPVTNG.EQ.1 ) THEN ISUB = IWORK( I ) JSUB = J ELSE IF( IPVTNG.EQ.2 ) THEN ISUB = I JSUB = IWORK( J ) ELSE IF( IPVTNG.EQ.3 ) THEN ISUB = IWORK( I ) JSUB = IWORK( J ) END IF * * Compute entry and grade it according to IGRADE * IF( ISUB.EQ.JSUB ) THEN TEMP = D( ISUB ) ELSE TEMP = DLARND( IDIST, ISEED ) END IF IF( IGRADE.EQ.1 ) THEN TEMP = TEMP*DL( ISUB ) ELSE IF( IGRADE.EQ.2 ) THEN TEMP = TEMP*DR( JSUB ) ELSE IF( IGRADE.EQ.3 ) THEN TEMP = TEMP*DL( ISUB )*DR( JSUB ) ELSE IF( IGRADE.EQ.4 .AND. ISUB.NE.JSUB ) THEN TEMP = TEMP*DL( ISUB ) / DL( JSUB ) ELSE IF( IGRADE.EQ.5 ) THEN TEMP = TEMP*DL( ISUB )*DL( JSUB ) END IF DLATM2 = TEMP RETURN * * End of DLATM2 * END |