asymp.jl

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### GCMMA-MMA-Julia                                                                                  ### 
###                                                                                                  ###
### This file is part of GCMMA-MMA-Julia. GCMMA-MMA-Julia is licensed under the terms of GNU         ###
### General Public License as published by the Free Software Foundation. For more information and    ###
### the LICENSE file, see <https://github.com/pollinico/GCMMA-MMA-Julia/blob/main/LICENSE>.          ###
###                                                                                                  ###
### The orginal work is written by Krister Svanberg in MATLAB.                                       ###
### This is the Julia version of the code written by Nicolò Pollini.                                 ###
### version 18-05-2023                                                                               ###
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#-------------------------------------------------------------
#
#    Copyright (C) 2007 Krister Svanberg
#
#    This file, asymp.m, is part of GCMMA-MMA-code.
#    
#    GCMMA-MMA-code is free software; you can redistribute it and/or
#    modify it under the terms of the GNU General Public License as 
#    published by the Free Software Foundation; either version 3 of 
#    the License, or (at your option) any later version.
#    
#    This code is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#    
#    You should have received a copy of the GNU General Public License
#    (file COPYING) along with this file.  If not, see 
#    <http://www.gnu.org/licenses/>.
#    
#    You should have received a file README along with this file,
#    containing contact information.  If not, see
#    <http://www.smoptit.se/> or e-mail mmainfo@smoptit.se or krille@math.kth.se.
#
#------
#
#  Values on the parameters raa0, raa, low and upp are
#  calculated in the beginning of each outer iteration.
#
function asymp(outeriter,n,xval,xold1,xold2,xmin,xmax,low,upp,raa0,raa,raa0eps,raaeps,df0dx,dfdx);
    #
    eeen = ones(n)
    xmami = xmax - xmin
    xmamieps = 0.00001*eeen
    xmami = max.(xmami,xmamieps)
    raa0 = abs.(df0dx)'*xmami
    raa0 = max.(raa0eps,(0.1/n)*raa0)
    raa  = abs.(dfdx)*xmami
    raa  = max.(raaeps,(0.1/n)*raa)
    if outeriter < 2.5
        low = xval - 0.5*xmami
        upp = xval + 0.5*xmami
    else
        xxx = (xval-xold1).*(xold1-xold2)
        factor = copy(eeen)
        factor[findall(x -> x>0, xxx)] .= 1.2
        factor[findall(x -> x<0, xxx)] .= 0.7
        low = xval - factor.*(xold1 - low)
        upp = xval + factor.*(upp - xold1)
        lowmin = xval - 10*xmami
        lowmax = xval - 0.01*xmami
        uppmin = xval + 0.01*xmami
        uppmax = xval + 10*xmami
        low = max.(low,lowmin)
        low = min.(low,lowmax)
        upp = min.(upp,uppmax)
        upp = max.(upp,uppmin)
    end
    return low,upp,raa0,raa
end
#---------------------------------------------------------------------