84 lines
2.5 KiB
Fortran
84 lines
2.5 KiB
Fortran
SUBROUTINE SB08NY( DA, A, B, EPSB )
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C
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C SLICOT RELEASE 5.0.
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C
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C Copyright (c) 2002-2009 NICONET e.V.
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C
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C This program is free software: you can redistribute it and/or
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C modify it under the terms of the GNU General Public License as
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C published by the Free Software Foundation, either version 2 of
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C the License, or (at your option) any later version.
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C
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C This program is distributed in the hope that it will be useful,
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C but WITHOUT ANY WARRANTY; without even the implied warranty of
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C MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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C GNU General Public License for more details.
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C
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C You should have received a copy of the GNU General Public License
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C along with this program. If not, see
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C <http://www.gnu.org/licenses/>.
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C
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C PURPOSE
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C
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C To compute the coefficients of B(z) = A(1/z) * A(z) and a norm for
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C the accuracy of the computed coefficients.
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C
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C ARGUMENTS
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C
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C Input/Output Parameters
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C
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C DA (input) INTEGER
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C The degree of the polynomials A(z) and B(z). DA >= 0.
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C
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C A (input) DOUBLE PRECISION array, dimension (DA+1)
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C This array must contain the coefficients of the polynomial
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C A(z) in increasing powers of z.
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C
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C B (output) DOUBLE PRECISION array, dimension (DA+1)
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C This array contains the coefficients of the polynomial
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C B(z).
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C
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C EPSB (output) DOUBLE PRECISION
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C A value used for checking the accuracy of the computed
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C coefficients.
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C
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C CONTRIBUTOR
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C
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C Release 3.0: V. Sima, Katholieke Univ. Leuven, Belgium, Aug. 1997.
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C Supersedes Release 2.0 routine SB08BZ by A.J. Geurts.
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C
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C REVISIONS
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C
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C -
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C
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C KEYWORDS
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C
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C Laplace transform, polynomial operations, spectral factorization.
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C
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C ******************************************************************
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C
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C .. Parameters ..
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DOUBLE PRECISION THREE
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PARAMETER ( THREE = 3.0D0 )
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C .. Scalar Arguments ..
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INTEGER DA
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DOUBLE PRECISION EPSB
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C .. Array Arguments ..
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DOUBLE PRECISION A(*), B(*)
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C .. Local Scalars ..
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INTEGER I
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C .. External Functions ..
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DOUBLE PRECISION DDOT, DLAMCH
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EXTERNAL DDOT, DLAMCH
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C .. Executable Statements ..
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C
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DO 20 I = 1, DA + 1
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B(I) = DDOT( DA-I+2, A(1), 1, A(I), 1 )
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20 CONTINUE
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C
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EPSB = THREE*DLAMCH( 'Epsilon' )*B(1)
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C
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RETURN
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C *** Last line of SB08NY ***
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END
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