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C @(#)ftanh.for 19.1 (ES0-DMD) 02/25/03 13:17:32
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C===========================================================================
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C Copyright (C) 1995 European Southern Observatory (ESO)
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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 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 You should have received a copy of the GNU General Public
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C License along with this program; if not, write to the Free
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C Software Foundation, Inc., 675 Massachusetss Ave, Cambridge,
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C Corresponding concerning ESO-MIDAS should be addressed as follows:
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C Internet e-mail: midas@eso.org
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C Postal address: European Southern Observatory
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C Data Management Division
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C Karl-Schwarzschild-Strasse 2
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C D 85748 Garching bei Muenchen
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C===========================================================================
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SUBROUTINE FTANH(X,NP,PARAM,Y1,DERIV)
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C+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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C.COPYRIGHT: Copyright (c) 1987 European Southern Observatory,
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C.VERSION: 1.0 ESO-FORTRAN Conversion, AA 18:01 - 21 DEC 1987
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C.LANGUAGE: F77+ESOext
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C--------------------------------------------------------------
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C Y = A1*SINH(A2+X*A3)
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DOUBLE PRECISION Y1,PARAM(NP),DERIV(NP),W
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W = PARAM(3)*X + PARAM(2)
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Y1 = PARAM(1)*DERIV(1)
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DERIV(2) = PARAM(1)/ (DCOSH(W)**2)